Add Java 21 testing, make Java 21 the default (#150)

.github/workflows/check.yml

@@ -43,22 +43,22 @@ jobs:
           java-version: '17'
           cache: 'gradle'
 
-      - name: Setup JDK 19
-        id: setup-java-19
+      - name: Setup JDK 21
+        id: setup-java-21
         uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '19'
+          java-version: '21'
           cache: 'gradle'
 
       - name: Set JAVA_HOME
-        run: echo "JAVA_HOME=${{ steps.setup-java-17.outputs.path }}" >> $GITHUB_ENV
+        run: echo "JAVA_HOME=${{ steps.setup-java-21.outputs.path }}" >> $GITHUB_ENV
 
       - name: Setup gradle properties
         run: |
           cat .github/env/${{ runner.os }}/gradle.properties >> gradle.properties
           echo >> gradle.properties
-          echo "org.gradle.java.installations.paths=${{ steps.setup-java-8.outputs.path }},${{ steps.setup-java-11.outputs.path }},${{ steps.setup-java-17.outputs.path }},${{ steps.setup-java-19.outputs.path }}" >> gradle.properties
+          echo "org.gradle.java.installations.paths=${{ steps.setup-java-8.outputs.path }},${{ steps.setup-java-11.outputs.path }},${{ steps.setup-java-17.outputs.path }},${{ steps.setup-java-21.outputs.path }}" >> gradle.properties
           echo "customDoubleParser=${{ matrix.customDoubleParser }}" >> gradle.properties
           cat gradle.properties
 

.github/workflows/publish.yml

@@ -22,7 +22,7 @@ jobs:
         uses: actions/setup-java@v3
         with:
           distribution: 'temurin'
-          java-version: '17'
+          java-version: '21'
           cache: 'gradle'
 
       - name: Set JAVA_HOME

buildSrc/src/main/groovy/io/deephaven/csv/Constants.groovy

@@ -1,7 +1,7 @@
 package io.deephaven.csv
 
 class Constants {
-    public static int LATEST_LTS = 17
+    public static int LATEST_LTS = 21
 
-    public static int[] TEST_VERSIONS = [8, 11, 17, 19]
+    public static int[] TEST_VERSIONS = [8, 11, 17, 21]
 }