Separate code coverage build from standard JDK builds (#739)

Resolves #738

.github/workflows/ci.yml

@@ -28,14 +28,6 @@ jobs:
         # run a full build, just as we would for a release (i.e. the `ossrh` profile), but don't use gpg
         # to sign artifacts, since we don't want to mess with storing signing credentials in CI:
         run: ${{env.MVN_CMD}} verify -Possrh -Dgpg.skip=true
-      - name: Code coverage
-        if:  matrix.java == '8'
-        run: |
-          ${{env.MVN_CMD}} clean clover:setup test
-          ${{env.MVN_CMD}} -pl . clover:clover clover:check coveralls:report \
-            -DrepoToken="${{ secrets.GITHUB_TOKEN }}" \
-            -DserviceName=github \
-            -DserviceBuildNumber="${{ env.GITHUB_RUN_ID }}"
 
   zulu:
     strategy:
@@ -89,3 +81,39 @@ jobs:
         # run a full build, just as we would for a release (i.e. the `ossrh` profile), but don't use gpg
         # to sign artifacts, since we don't want to mess with storing signing credentials in CI:
         run: ${{env.MVN_CMD}} verify -Possrh -Dgpg.skip=true
+
+  code-coverage:
+    # (commented out for now - see the comments in 'Wait to start' below for why.  Keeping this here as a placeholder
+    # as it may be better to use instead of an artificial delay once we no longer need to build on JDK 7):
+    #needs: zulu # wait until others finish so a coverage failure doesn't cancel others accidentally
+    runs-on: 'ubuntu-latest'
+    env:
+      MVN_CMD: ./mvnw --no-transfer-progress -B
+    steps:
+      - uses: actions/checkout@v3
+      - name: Set up JDK
+        uses: actions/setup-java@v3
+        with:
+          distribution: 'zulu'
+          java-version: '8'
+          cache: 'maven'
+          check-latest: true
+      - name: Wait to start
+        # wait a little to start: code coverage usually only takes about 1 1/2 minutes.  If coverage fails, it will
+        # cancel the other running builds, and we don't want that (because we want to see if jobs fail due to
+        # build issues, not due to the code-coverage job causing the others to cancel).  We could have used the
+        # 'need' property (commented out above), and that would wait until all the other jobs have finished before
+        # starting this one, but that introduces unnecessary (sometimes 2 1/2 minute) delay, whereas delaying the
+        # start of the code coverage checks a bit should allow everything to finish around the same time without having
+        # much of an adverse effect on the other jobs above.
+        run: sleep 90s
+        shell: bash
+      - name: Code Coverage
+        # run a full build, just as we would for a release (i.e. the `ossrh` profile), but don't use gpg
+        # to sign artifacts, since we don't want to mess with storing signing credentials in CI:
+        run: |
+          ${{env.MVN_CMD}} clover:setup test && \
+            ${{env.MVN_CMD}} -pl . clover:clover clover:check coveralls:report \
+              -DrepoToken="${{ secrets.GITHUB_TOKEN }}" \
+              -DserviceName=github \
+              -DserviceBuildNumber="${{ env.GITHUB_RUN_ID }}"