chore: add copyright headers

Make sure we obey the REUSE (https://reuse.software) specification and the
origin, copyright owner, and license of all files are clearly marked.

The whole project is under the EPL-2.0, except for trivial files where copyright
is not applicable that are marked with the CC0-1.0 license. Moreover, code
included from third parties is also available under the respective license.

chore: add CONTRIBUTORS.md

List all authors and supporting organizations in accordance with the REUSE
specification.

59 files changed, 301 insertions, 1 deletions

diff --git a/subprojects/language/build.gradle.kts b/subprojects/language/build.gradle.kts
index 4cfe6895..aa799c3b 100644
--- a/subprojects/language/build.gradle.kts
+++ b/subprojects/language/build.gradle.kts
@@ -1,3 +1,9 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
 import tools.refinery.gradle.utils.SonarPropertiesUtils
 
 plugins {
diff --git a/subprojects/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2 b/subprojects/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
index 21ff456e..d8d89173 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
+++ b/subprojects/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 module tools.refinery.language.GenerateProblem
 
 import org.eclipse.xtext.xtext.generator.*
@@ -55,7 +60,7 @@ Workflow {
                         }
                         webSupport = {
                                 // We only generate the {@code AbstractProblemWebModule},
-                                // because we write our own integration code for CodeMirror 6. 
+                                // because we write our own integration code for CodeMirror 6.
                                 framework = 'codemirror'
                                 generateHtmlExample = false
                                 generateJettyLauncher = false
diff --git a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
index 187ebf1f..9e330347 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/subprojects/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 grammar tools.refinery.language.Problem with org.eclipse.xtext.common.Terminals
 
 import "http://www.eclipse.org/emf/2002/Ecore" as ecore
diff --git a/subprojects/language/src/main/java/tools/refinery/language/ProblemRuntimeModule.java b/subprojects/language/src/main/java/tools/refinery/language/ProblemRuntimeModule.java
index 5efcdc81..2636a8ee 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/ProblemRuntimeModule.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/ProblemRuntimeModule.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.25.0
  */
 package tools.refinery.language;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/ProblemStandaloneSetup.java b/subprojects/language/src/main/java/tools/refinery/language/ProblemStandaloneSetup.java
index 41c96114..639d6778 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/ProblemStandaloneSetup.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/ProblemStandaloneSetup.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.25.0
  */
 package tools.refinery.language;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/conversion/ProblemValueConverterService.java b/subprojects/language/src/main/java/tools/refinery/language/conversion/ProblemValueConverterService.java
index 508688ed..afbc367e 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/conversion/ProblemValueConverterService.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/conversion/ProblemValueConverterService.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.conversion;
 
 import org.eclipse.xtext.common.services.DefaultTerminalConverters;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/conversion/UpperBoundValueConverter.java b/subprojects/language/src/main/java/tools/refinery/language/conversion/UpperBoundValueConverter.java
index be0d15ad..4886757d 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/conversion/UpperBoundValueConverter.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/conversion/UpperBoundValueConverter.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.conversion;
 
 import org.eclipse.xtext.conversion.ValueConverterException;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/formatting2/ProblemFormatter.java b/subprojects/language/src/main/java/tools/refinery/language/formatting2/ProblemFormatter.java
index 797535ea..55a5ac20 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/formatting2/ProblemFormatter.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/formatting2/ProblemFormatter.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.26.0.M2
  */
 package tools.refinery.language.formatting2;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/naming/NamingUtil.java b/subprojects/language/src/main/java/tools/refinery/language/naming/NamingUtil.java
index e959be74..1647d4e7 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/naming/NamingUtil.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/naming/NamingUtil.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.naming;
 
 import java.util.regex.Pattern;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/naming/ProblemQualifiedNameConverter.java b/subprojects/language/src/main/java/tools/refinery/language/naming/ProblemQualifiedNameConverter.java
index 5453906f..74b4e208 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/naming/ProblemQualifiedNameConverter.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/naming/ProblemQualifiedNameConverter.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.naming;
 
 import org.eclipse.xtext.naming.IQualifiedNameConverter;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/IdentifierTokenProvider.java b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/IdentifierTokenProvider.java
index ab133a90..306a86fc 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/IdentifierTokenProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/IdentifierTokenProvider.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.parser.antlr;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/ProblemTokenSource.java b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/ProblemTokenSource.java
index 0b4e7185..5b91a6cc 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/ProblemTokenSource.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/ProblemTokenSource.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.29.0.M2
  */
 package tools.refinery.language.parser.antlr;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/TokenSourceInjectingProblemParser.java b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/TokenSourceInjectingProblemParser.java
index 0cdd38d8..fe4c0bc7 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/TokenSourceInjectingProblemParser.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/parser/antlr/TokenSourceInjectingProblemParser.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.parser.antlr;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/DerivedVariableComputer.java b/subprojects/language/src/main/java/tools/refinery/language/resource/DerivedVariableComputer.java
index 6176b0c4..07c5da41 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/DerivedVariableComputer.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/DerivedVariableComputer.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/ImplicitVariableScope.java b/subprojects/language/src/main/java/tools/refinery/language/resource/ImplicitVariableScope.java
index b0ac2ab6..e97c8287 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/ImplicitVariableScope.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/ImplicitVariableScope.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import org.eclipse.emf.ecore.EObject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/NodeNameCollector.java b/subprojects/language/src/main/java/tools/refinery/language/resource/NodeNameCollector.java
index 419be0d3..e5deca4d 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/NodeNameCollector.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/NodeNameCollector.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import com.google.common.collect.ImmutableSet;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemDerivedStateComputer.java b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemDerivedStateComputer.java
index 8d3a552a..b145ef27 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemDerivedStateComputer.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemDerivedStateComputer.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemLocationInFileProvider.java b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemLocationInFileProvider.java
index df822987..1fe2df89 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemLocationInFileProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemLocationInFileProvider.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import org.eclipse.emf.ecore.EObject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemResourceDescriptionStrategy.java b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemResourceDescriptionStrategy.java
index 1a0b73a8..630be379 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemResourceDescriptionStrategy.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/ProblemResourceDescriptionStrategy.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import org.eclipse.emf.ecore.EObject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/resource/ReferenceCounter.java b/subprojects/language/src/main/java/tools/refinery/language/resource/ReferenceCounter.java
index ca20325e..f1be55ee 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/resource/ReferenceCounter.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/resource/ReferenceCounter.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.resource;
 
 import java.util.HashMap;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemGlobalScopeProvider.java b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemGlobalScopeProvider.java
index b749154c..4d2dd772 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemGlobalScopeProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemGlobalScopeProvider.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.scoping;
 
 import java.util.LinkedHashSet;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemLocalScopeProvider.java b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemLocalScopeProvider.java
index 61883f0e..229960a0 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemLocalScopeProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemLocalScopeProvider.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.scoping;
 
 import java.util.List;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
index 3ab07496..cf099aba 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/scoping/ProblemScopeProvider.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.25.0
  */
 package tools.refinery.language.scoping;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/serializer/PreferShortAssertionsProblemSemanticSequencer.java b/subprojects/language/src/main/java/tools/refinery/language/serializer/PreferShortAssertionsProblemSemanticSequencer.java
index 27ce1521..b9cafbc2 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/serializer/PreferShortAssertionsProblemSemanticSequencer.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/serializer/PreferShortAssertionsProblemSemanticSequencer.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.serializer;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/BuiltinSymbols.java b/subprojects/language/src/main/java/tools/refinery/language/utils/BuiltinSymbols.java
index d3777cd3..c8c7fd4a 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/BuiltinSymbols.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/BuiltinSymbols.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import tools.refinery.language.model.problem.*;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/CollectedSymbols.java b/subprojects/language/src/main/java/tools/refinery/language/utils/CollectedSymbols.java
index b5682f32..e4e4d07a 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/CollectedSymbols.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/CollectedSymbols.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import java.util.Map;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/ContainmentRole.java b/subprojects/language/src/main/java/tools/refinery/language/utils/ContainmentRole.java
index 708e10a9..a43c7dfe 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/ContainmentRole.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/ContainmentRole.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import tools.refinery.language.model.problem.PredicateKind;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/NodeInfo.java b/subprojects/language/src/main/java/tools/refinery/language/utils/NodeInfo.java
index c8f47653..0fa7a454 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/NodeInfo.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/NodeInfo.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 public record NodeInfo(String name, boolean individual) {
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemDesugarer.java b/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemDesugarer.java
index b8200919..738a0896 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemDesugarer.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemDesugarer.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemUtil.java b/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemUtil.java
index 1e5164d3..9486dc2a 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemUtil.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/ProblemUtil.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import org.eclipse.emf.common.util.URI;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/RelationInfo.java b/subprojects/language/src/main/java/tools/refinery/language/utils/RelationInfo.java
index 2253d257..1c46fe72 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/RelationInfo.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/RelationInfo.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import tools.refinery.language.model.problem.*;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/utils/SymbolCollector.java b/subprojects/language/src/main/java/tools/refinery/language/utils/SymbolCollector.java
index 65167ed6..a4ea1113 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/utils/SymbolCollector.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/utils/SymbolCollector.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.utils;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/main/java/tools/refinery/language/validation/ProblemValidator.java b/subprojects/language/src/main/java/tools/refinery/language/validation/ProblemValidator.java
index 659d882c..88d50c5b 100644
--- a/subprojects/language/src/main/java/tools/refinery/language/validation/ProblemValidator.java
+++ b/subprojects/language/src/main/java/tools/refinery/language/validation/ProblemValidator.java
@@ -1,4 +1,10 @@
 /*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
+/*
  * generated by Xtext 2.25.0
  */
 package tools.refinery.language.validation;
diff --git a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
index 06b6da1d..9c1d7669 100644
--- a/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
+++ b/subprojects/language/src/main/resources/tools/refinery/language/builtin.problem
@@ -1,3 +1,6 @@
+% SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+%
+% SPDX-License-Identifier: EPL-2.0
 problem builtin.
 
 abstract class node {
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/ProblemParsingTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/ProblemParsingTest.java
index 58daa365..c7952369 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/ProblemParsingTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/ProblemParsingTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/formatting2/ProblemFormatterTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/formatting2/ProblemFormatterTest.java
index 6e0802ca..f688d970 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/formatting2/ProblemFormatterTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/formatting2/ProblemFormatterTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.formatting2;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/IdentifierTokenProviderTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/IdentifierTokenProviderTest.java
index abff8d9c..37d38dd9 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/IdentifierTokenProviderTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/IdentifierTokenProviderTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.parser.antlr;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/ProblemTokenSourceTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/ProblemTokenSourceTest.java
index cb42d5d0..644744a0 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/ProblemTokenSourceTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/ProblemTokenSourceTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.parser.antlr;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/TransitiveClosureParserTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/TransitiveClosureParserTest.java
index 65ceb45f..1180d131 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/TransitiveClosureParserTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/parser/antlr/TransitiveClosureParserTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.parser.antlr;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/rules/RuleParsingTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/rules/RuleParsingTest.java
index 72e5e18a..68514bfa 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/rules/RuleParsingTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/rules/RuleParsingTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.rules;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/scoping/NodeScopingTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/scoping/NodeScopingTest.java
index fa462691..734bfcd1 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/scoping/NodeScopingTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/scoping/NodeScopingTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.scoping;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/serializer/ProblemSerializerTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/serializer/ProblemSerializerTest.java
index 4a18704a..3f3a081f 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/serializer/ProblemSerializerTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/serializer/ProblemSerializerTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.serializer;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/test/java/tools/refinery/language/tests/utils/SymbolCollectorTest.java b/subprojects/language/src/test/java/tools/refinery/language/tests/utils/SymbolCollectorTest.java
index af6de37f..d200eeff 100644
--- a/subprojects/language/src/test/java/tools/refinery/language/tests/utils/SymbolCollectorTest.java
+++ b/subprojects/language/src/test/java/tools/refinery/language/tests/utils/SymbolCollectorTest.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.tests.utils;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemNavigationUtil.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemNavigationUtil.java
index 5761935b..d92011a9 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemNavigationUtil.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemNavigationUtil.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import java.util.List;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemParseHelper.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemParseHelper.java
index 5e044a94..6f6a87f7 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemParseHelper.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/ProblemParseHelper.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import org.eclipse.xtext.testing.util.ParseHelper;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAction.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAction.java
index d176727b..3a49a0b9 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAction.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAction.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Action;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedArgument.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedArgument.java
index 9e4c59f5..ed749fed 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedArgument.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedArgument.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.*;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertion.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertion.java
index 2c38639d..b2ef6e48 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertion.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertion.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Assertion;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertionArgument.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertionArgument.java
index 840c1f74..b36f2506 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertionArgument.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAssertionArgument.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.AssertionArgument;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAtom.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAtom.java
index 498991f8..c02f447b 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAtom.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedAtom.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Atom;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedClassDeclaration.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedClassDeclaration.java
index 41b2ea62..a228137c 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedClassDeclaration.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedClassDeclaration.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.ClassDeclaration;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConjunction.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConjunction.java
index 88ff71ab..b126b1ce 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConjunction.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConjunction.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Conjunction;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConsequent.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConsequent.java
index 46faa7da..8d6a92f8 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConsequent.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedConsequent.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Consequent;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedEnumDeclaration.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedEnumDeclaration.java
index 74dcf01b..229a8c0a 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedEnumDeclaration.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedEnumDeclaration.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.EnumDeclaration;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedLiteral.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedLiteral.java
index 4aa71b99..160e5dd8 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedLiteral.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedLiteral.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Atom;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedParametricDefinition.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedParametricDefinition.java
index c2f18a60..d44b79ed 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedParametricDefinition.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedParametricDefinition.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.Parameter;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedPredicateDefinition.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedPredicateDefinition.java
index 7b95ecc1..2cf5fd89 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedPredicateDefinition.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedPredicateDefinition.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.PredicateDefinition;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedProblem.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedProblem.java
index 78ca95c7..e5aa0043 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedProblem.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedProblem.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import org.eclipse.emf.ecore.resource.Resource.Diagnostic;
diff --git a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedRuleDefinition.java b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedRuleDefinition.java
index a4cf2eaf..326d8ec3 100644
--- a/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedRuleDefinition.java
+++ b/subprojects/language/src/testFixtures/java/tools/refinery/language/model/tests/utils/WrappedRuleDefinition.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.language.model.tests.utils;
 
 import tools.refinery.language.model.problem.RuleDefinition;