Move spotless check to separate build task (#1946)

This means the tests can run in parallel of the formatting changes.
Therefore, formatting changes would not block obtaining your test
results, which should hopefully reduce the amount of Travis builds
necessary to work on a community PR.

This is also in preparation of #1934 which requires spotless to
run on JDK11 minimum.

.travis.yml

@@ -34,8 +34,16 @@ matrix:
     env: SKIP_RELEASE=true
   - jdk: openjdk11
     env: SKIP_RELEASE=true MOCK_MAKER=mock-maker-inline
+    # Run Spotless as a separate job on JDK 11 (which is required for google-java-format)
+  - jdk: openjdk11
+    name: "Verify code formatting with Spotless"
+    script: ./gradlew spotlessCheck
+    # Do not upload a coverage report, as we don't run the tests for this job
+    after_success: true
   - jdk: openjdk8
+    name: "Check reproducibility of jars"
     script: ./check_reproducibility.sh
+    # Do not upload a coverage report, as we don't run the tests for this job
     after_success: true
 
 branches:
@@ -53,7 +61,7 @@ script:
   # We are using && below on purpose
   # ciPerformRelease must run only when the entire build has completed
   # This guarantees that no release steps are executed when the build or tests fail
-  - ./gradlew spotlessCheck && ./gradlew build idea -s && ./gradlew ciPerformRelease
+  - ./gradlew build idea -s && ./gradlew ciPerformRelease
 
 after_success:
   #Generates coverage report:

settings.gradle.kts

@@ -1,3 +1,7 @@
+plugins {
+  id("com.gradle.enterprise").version("3.3.4")
+}
+
 include("deprecatedPluginsTest",
     "inline",
     "extTest",
@@ -34,10 +38,6 @@ rootProject.children.forEach { project ->
     }
 }
 
-plugins {
-  id("com.gradle.enterprise").version("3.3.4")
-}
-
 //Posting Build scans to https://scans.gradle.com
 gradleEnterprise {
     buildScan {