Add CI matrix for jdk 8, 11 and 14 (#145)

* Add CI matrix for jdk 8, 11 and 14

Signed-off-by: Sagar Upadhyaya <[email protected]>

* Adding check to not add javadoc options for jdk 8

Signed-off-by: Sagar Upadhyaya <[email protected]>

Author: sgup432

.github/workflows/gradle.yml

@@ -11,13 +11,19 @@ on:
 
 jobs:
   build_rca_pkg:
+    strategy:
+      matrix:
+        java:
+          - 8
+          - 11
+          - 14
     runs-on: [ubuntu-latest]
     name: Building RCA package
     steps:
     - name: Set up JDK
       uses: actions/setup-java@v1
       with:
-        java-version: 14
+        java-version: ${{matrix.java}}
 
     # RCA in ./tmp/performance-analyzer-rca
     - name: Checkout RCA

DEVELOPER_GUIDE.md

@@ -1,7 +1,7 @@
 - [Developer Guide](#developer-guide)
   - [Forking and Cloning](#forking-and-cloning)
   - [Install Prerequisites](#install-prerequisites)
-    - [JDK 14](#jdk-14)
+    - [JDK 11](#jdk-11)
   - [Building](#building)
   - [Using IntelliJ IDEA](#using-intellij-idea)
   - [Submitting Changes](#submitting-changes)
@@ -16,9 +16,9 @@ Fork this repository on GitHub, and clone locally with `git clone`.
 
 ### Install Prerequisites
 
-#### JDK 14
+#### JDK 11
 
-OpenSearch components build using Java 14 at a minimum. This means you must have a JDK 14 installed with the environment variable `JAVA_HOME` referencing the path to Java home for your JDK 14 installation, e.g. `JAVA_HOME=/usr/lib/jvm/jdk-14`.
+OpenSearch components build using Java 11 at a minimum. This means you must have a JDK 11 installed with the environment variable `JAVA_HOME` referencing the path to Java home for your JDK 11 installation, e.g. `JAVA_HOME=/usr/lib/jvm/jdk-11`.
 
 ### Building