chore: upgrade to Eclipse 2023-12

Updates references to Eclipse in documentation (but IntelliJ is the preferred
editor now).

Also fixes incompatibilities with the Eclipse compiler.

4 files changed, 24 insertions, 19 deletions

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d5191795..a5f1594a 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -8,41 +8,44 @@
 
 ## Setting up the development environment
 
+### With IntelliJ IDEA
+
+We prefer IntelliJ IDEA as a development environment.
+No special preparations should be necessary for importing the project as a Gradle project into IDEA.
+
+However, you will need Eclipse to edit Xtext (`*.xtext`) and MWE2 (`*.mwe2`) files and Ecore class diagrams (`*.aird`, `*.ecore`, `*.genmodel`).
+If you do not plan on making changes to such files, feel free to skip the Eclipse installation steps below.
+
 ### With Eclipse IDE
 
-1. Download and install a _Java 17_ compatible JDK. For Windows, prefer OpenJDK builds from [Adoptium](https://adoptium.net/).
+1. Download and install a _Java 21_ compatible JDK. For Windows, prefer OpenJDK builds from [Adoptium](https://adoptium.net/).
 
-2. Download and extract the [Eclipse IDE for Java and DSL Developers 2022-09](https://www.eclipse.org/downloads/packages/release/2022-09/r/eclipse-ide-java-and-dsl-developers) package.
+2. Download and extract the [Eclipse IDE for Java and DSL Developers 2023-12](https://www.eclipse.org/downloads/packages/release/2023-12/r/eclipse-ide-java-and-dsl-developers) package.
 
 3. Launch Eclipse and create a new workspace.
 
-4. Open _Help > Install New Software..._ and install the following software from the _2022-09_ update site:
-    * _Modeling > Ecore Diagram Editor (SDK)_
-
-5. Open _Help > Eclipse Marketplace_ and install the following software:
+4. Open _Help > Eclipse Marketplace_ and install the following software:
     * _EclEmma Java Code Coverage_
+    * _EcoreTools : Ecore Diagram Editor_
+    * _Sirius_ (ignore the warning during installation about the solution _Sirius_ not being available)
     * _SonarLint_
 
-6. Open _Window > Preferences_ and set the following preferences:
+5. Open _Window > Preferences_ and set the following preferences:
     * _General > Workspace > Text file encoding_ should be _UTF-8_.
     * _General > Workspace > New text file line delimiter_ should be _Unix_.
-    * Add the JDK 17 to _Java > Installed JREs_.
-    * Make sure JDK 17 is selected for _JavaSE-17_ at _Java > Installed JREs > Execution Environments_.
-    * Set _Gradle > Java home_ to the `JAVA_HOME` directory (the directory which contains the `bin` directory) of JDK 17. Here, Buildship will show a yellow warning sign, which can be safely ignored.
-    * Set _Java > Compiler > JDK Compliance > Compiler compliance level_ to _17_.
+    * Add the JDK 21 to _Java > Installed JREs_.
+    * Make sure JDK 21 is selected for _JavaSE-21_ at _Java > Installed JREs > Execution Environments_.
+    * Set _Gradle > Java home_ to the `JAVA_HOME` directory (the directory which contains the `bin` directory) of JDK 21. Here, Buildship will show a yellow warning sign, which can be safely ignored.
+    * Set _Java > Compiler > JDK Compliance > Compiler compliance level_ to _21_.
 
-7. Clone the project Git repository but do not import it into Eclipse yet.
+6. Clone the project Git repository but do not import it into Eclipse yet.
 
-8. Open a new terminal an run `./gradlew prepareEclipse` (`.\gradlew prepareEclipse` on Windows) in the cloned repository.
+7. Open a new terminal an run `./gradlew prepareEclipse` (`.\gradlew prepareEclipse` on Windows) in the cloned repository.
     * This should complete without any compilation errors.
     * If you get any errors about the JVM version, check whether the `JAVA_HOME` environment variable is set to the location of JDK. You can query the variable with `echo $JAVA_HOME` on Linux and `echo $Env:JAVA_HOME` in PowerShell on Windows. To set it, use `export JAVA_HOME=/java/path/here` or `$Env:JAVA_HOME="C:\java\path\here"`, respectively.
     * If the build fails with a `Host name must not be empty` error, you [might need to remove the empty proxy configuration from your global `gradle.properties` file](https://stackoverflow.com/a/62128323).
 
-9. Select _File > Import... > Gradle > Existing Gradle Project_ and import the cloned repository in Eclipse.
+8. Select _File > Import... > Gradle > Existing Gradle Project_ and import the cloned repository in Eclipse.
     * Make sure to select the root of the repository (containing this file) as the _Project root directory_ and that the _Gradle distribution_ is _Gradle wrapper_.
     * If you have previously imported the project into Eclipse, this step will likely fail. In that case, you should remove the projects from Eclipse, run `git clean -fxd` in the repository, and start over from step 8.
 
-### With IntelliJ IDEA
-
-It is possible to import the project into IntelliJ IDEA, but it gives no editing help for Xtext (`*.xtext`), MWE2 (`*.mwe2`), and Xtend (`*.xtend`) and Ecore class diagrams (`*.aird`, `*.ecore`, `*.genmodel`).
-
diff --git a/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulParallelTimelyColumnAggregatorNode.java b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulParallelTimelyColumnAggregatorNode.java
index 13cd9662..b1e0e390 100644
--- a/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulParallelTimelyColumnAggregatorNode.java
+++ b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulParallelTimelyColumnAggregatorNode.java
@@ -15,6 +15,7 @@ import tools.refinery.interpreter.matchers.util.*;
 import tools.refinery.interpreter.matchers.util.timeline.Diff;
 import tools.refinery.interpreter.rete.aggregation.timely.FaithfulParallelTimelyColumnAggregatorNode.CumulativeAggregate;
 import tools.refinery.interpreter.rete.aggregation.timely.FaithfulParallelTimelyColumnAggregatorNode.FoldingState;
+import tools.refinery.interpreter.rete.aggregation.timely.FaithfulTimelyColumnAggregatorNode.MergeableFoldingState;
 import tools.refinery.interpreter.rete.network.ReteContainer;
 import tools.refinery.interpreter.rete.network.communication.Timestamp;
 import tools.refinery.interpreter.rete.network.communication.timely.ResumableNode;
diff --git a/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulSequentialTimelyColumnAggregatorNode.java b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulSequentialTimelyColumnAggregatorNode.java
index 72e52f7e..62c1f59f 100644
--- a/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulSequentialTimelyColumnAggregatorNode.java
+++ b/subprojects/interpreter-rete/src/main/java/tools/refinery/interpreter/rete/aggregation/timely/FaithfulSequentialTimelyColumnAggregatorNode.java
@@ -25,6 +25,7 @@ import tools.refinery.interpreter.matchers.util.Signed;
 import tools.refinery.interpreter.matchers.util.timeline.Diff;
 import tools.refinery.interpreter.rete.aggregation.timely.FaithfulSequentialTimelyColumnAggregatorNode.CumulativeAggregate;
 import tools.refinery.interpreter.rete.aggregation.timely.FaithfulSequentialTimelyColumnAggregatorNode.FoldingState;
+import tools.refinery.interpreter.rete.aggregation.timely.FaithfulTimelyColumnAggregatorNode.MergeableFoldingState;
 import tools.refinery.interpreter.rete.network.ReteContainer;
 import tools.refinery.interpreter.rete.network.communication.Timestamp;
 import tools.refinery.interpreter.rete.network.communication.timely.ResumableNode;
diff --git a/subprojects/store/src/test/java/tools/refinery/store/model/hashtests/HashEfficiencyTest.java b/subprojects/store/src/test/java/tools/refinery/store/model/hashtests/HashEfficiencyTest.java
index 5b595da7..cbc60a01 100644
--- a/subprojects/store/src/test/java/tools/refinery/store/model/hashtests/HashEfficiencyTest.java
+++ b/subprojects/store/src/test/java/tools/refinery/store/model/hashtests/HashEfficiencyTest.java
@@ -3,7 +3,7 @@
  *
  * SPDX-License-Identifier: EPL-2.0
  */
-package tools.refinery.store.model.hashTests;
+package tools.refinery.store.model.hashtests;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;