GitHub actions/setup-java@v1 -> actions/setup-java@v1.4.0.
diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 5924734..dd3919a 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -33,7 +33,7 @@
     steps:
     - uses: actions/checkout@v2.3.1
     - name: Set up JDK ${{ matrix.java }}
-      uses: actions/setup-java@v1
+      uses: actions/setup-java@v1.4.0
       with:
         java-version: ${{ matrix.java }}
     - name: Build with Maven