Improve build pipeline.

.github/workflows/gradle.yml

@@ -1,26 +1,30 @@
 name: JPX Build
 
 on:
-  push:
-    branches:
-      - main
-      - releases/*
-      - issues/*
-  pull_request:
-    branches:
-      - main
-      - releases/*
+    push:
+        branches:
+            - master
+            - releases/*
+            - issues/*
+    pull_request:
+        branches:
+            - master
+            - releases/*
 
 jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
+    build:
+        runs-on: ${{ matrix.os }}
+        strategy:
+            matrix:
+                os: [ ubuntu-latest, macos-latest ]
+                java-version: [ 17, 18-ea  ]
+        steps:
+            - uses: actions/checkout@v2
 
-    - name: Set up JDK 17
-      uses: actions/setup-java@v2
-      with:
-        java-version: '17'
-        distribution: 'adopt'
-    - name: Build with Gradle
-      run: ./gradlew build
+            - name: Set up JDK ${{ matrix.java-version }} on ${{ matrix.os }}
+              uses: actions/setup-java@v2
+              with:
+                  java-version: ${{ matrix.java-version }}
+                  distribution: 'zulu'
+            - name: Build with Gradle
+              run: ./gradlew build --stacktrace --info