[Travis] Replace JDK 9/10 with 14 (#1945)

9/10 are EOL since September 2018. 14 is the currently supported
Java version.

.travis.yml

@@ -20,20 +20,14 @@ matrix:
   - jdk: openjdk8
   - jdk: openjdk8
     env: SKIP_RELEASE=true MOCK_MAKER=mock-maker-inline
-  - jdk: openjdk9
-    env: SKIP_RELEASE=true
-  - jdk: openjdk9
-    env: SKIP_RELEASE=true MOCK_MAKER=mock-maker-inline
-  - jdk: openjdk9
-    env: SKIP_RELEASE=true SIMULATE_JAVA11=true
-  - jdk: openjdk10
-    env: SKIP_RELEASE=true
-  - jdk: openjdk10
-    env: SKIP_RELEASE=true MOCK_MAKER=mock-maker-inline
   - jdk: openjdk11
     env: SKIP_RELEASE=true
   - jdk: openjdk11
     env: SKIP_RELEASE=true MOCK_MAKER=mock-maker-inline
+  - jdk: openjdk14
+    env: SKIP_RELEASE=true
+  - jdk: openjdk14
+    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"