Run GitHub actions on PRs and merge all workflows to one file

.github/workflows/maven.yml

@@ -1,17 +1,30 @@
-name: jdk8
+name: Java tests
 
-on: [push]
+on:
+  push:
+  pull_request:
 
 jobs:
   build:
-
     runs-on: ubuntu-latest
 
+    strategy:
+      matrix:
+        java:
+          - '8'
+          - '11'
+          - '17'
+
+    name: Java ${{ matrix.java }}
     steps:
-    - uses: actions/checkout@v1
-    - name: Set up JDK 1.8
-      uses: actions/setup-java@v1
+    - uses: actions/checkout@v3
+
+    - name: Set up Eclipse Temurin ${{ matrix.java }}
+      uses: actions/setup-java@v4
       with:
-        java-version: 1.8
+        distribution: temurin
+        java-version: ${{ matrix.java }}
+        cache: 'maven'
+
     - name: Build with Maven
       run: mvn -B package --file pom.xml