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.

9 files changed, 46 insertions, 0 deletions

diff --git a/subprojects/language-semantics/build.gradle.kts b/subprojects/language-semantics/build.gradle.kts
index bf016dc9..38cd9e0d 100644
--- a/subprojects/language-semantics/build.gradle.kts
+++ b/subprojects/language-semantics/build.gradle.kts
@@ -1,3 +1,9 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+
 plugins {
         id("tools.refinery.gradle.java-library")
 }
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/ModelInitializer.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/ModelInitializer.java
index a6712a89..41b4fcb0 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/ModelInitializer.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/ModelInitializer.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.semantics.model;
 
 import com.google.inject.Inject;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTree.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTree.java
index 55edee6d..c1afecf9 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTree.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTree.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.semantics.model.internal;
 
 import org.eclipse.collections.api.factory.primitive.IntObjectMaps;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeCursor.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeCursor.java
index fdf8e452..9a1e15a3 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeCursor.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeCursor.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.semantics.model.internal;
 
 import tools.refinery.store.map.Cursor;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeNode.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeNode.java
index b81ea3fe..3c54e3c5 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeNode.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeNode.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.semantics.model.internal;
 
 import org.eclipse.collections.api.LazyIntIterable;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeValue.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeValue.java
index 495a53dd..915ae2bf 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeValue.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/DecisionTreeValue.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.semantics.model.internal;
 
 import tools.refinery.store.representation.TruthValue;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/IntermediateNode.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/IntermediateNode.java
index c4200509..e6f01d48 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/IntermediateNode.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/IntermediateNode.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.semantics.model.internal;
 
 import org.eclipse.collections.api.LazyIntIterable;
diff --git a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/TerminalNode.java b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/TerminalNode.java
index 4af836ff..ce49aa62 100644
--- a/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/TerminalNode.java
+++ b/subprojects/language-semantics/src/main/java/tools/refinery/language/semantics/model/internal/TerminalNode.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.semantics.model.internal;
 
 import org.eclipse.collections.api.LazyIntIterable;
diff --git a/subprojects/language-semantics/src/test/java/tools/refinery/language/semantics/model/tests/DecisionTreeTests.java b/subprojects/language-semantics/src/test/java/tools/refinery/language/semantics/model/tests/DecisionTreeTests.java
index 4630bf53..b3fcbabb 100644
--- a/subprojects/language-semantics/src/test/java/tools/refinery/language/semantics/model/tests/DecisionTreeTests.java
+++ b/subprojects/language-semantics/src/test/java/tools/refinery/language/semantics/model/tests/DecisionTreeTests.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.semantics.model.tests;
 
 import org.junit.jupiter.api.Test;