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.

2 files changed, 10 insertions, 0 deletions

diff --git a/buildSrc/src/main/java/tools/refinery/gradle/utils/EclipseUtils.java b/buildSrc/src/main/java/tools/refinery/gradle/utils/EclipseUtils.java
index 1e33a95d..ac7ba3f4 100644
--- a/buildSrc/src/main/java/tools/refinery/gradle/utils/EclipseUtils.java
+++ b/buildSrc/src/main/java/tools/refinery/gradle/utils/EclipseUtils.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.gradle.utils;
 
 import groovy.lang.Closure;
diff --git a/buildSrc/src/main/java/tools/refinery/gradle/utils/SonarPropertiesUtils.java b/buildSrc/src/main/java/tools/refinery/gradle/utils/SonarPropertiesUtils.java
index 3810fccf..183cd56a 100644
--- a/buildSrc/src/main/java/tools/refinery/gradle/utils/SonarPropertiesUtils.java
+++ b/buildSrc/src/main/java/tools/refinery/gradle/utils/SonarPropertiesUtils.java
@@ -1,3 +1,8 @@
+/*
+ * SPDX-FileCopyrightText: 2021-2023 The Refinery Authors <https://refinery.tools/>
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
 package tools.refinery.gradle.utils;
 
 import java.util.ArrayList;