created the method decreaseValue synchronized

Author: StoneBlood-bit

.github/workflows/ci.yml

@@ -12,7 +12,7 @@ jobs:
           ref: ${{github.event.pull_request.head.ref}}
           repository: ${{github.event.pull_request.head.repo.full_name}}
       - name: Set up JDK 17
-        uses: actions/setup-java@v3
+        uses: actions/setup-java@v2
         with:
           java-version: '17'
           distribution: 'adopt'