Build with Java 15
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 096995c..58fa126 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -24,7 +24,7 @@
   build:
     strategy:
       matrix:
-        java: [ 8, 11 ]
+        java: [ 8, 11, 15 ]
     name: "Java ${{ matrix.java }}"
     runs-on: ubuntu-18.04
     steps: