fixed user group to 'docker' for non-root backend execution in docker container

Dockerfile

@@ -26,7 +26,8 @@ COPY --from=corretto-jdk /customjre $JAVA_HOME
 
 # Add app user
 ARG APPLICATION_USER=appuser
-RUN adduser --no-create-home -u 1000 -D $APPLICATION_USER
+RUN addgroup -g 137 -S docker
+RUN adduser --no-create-home -u 1000 -G docker -D $APPLICATION_USER
 
 # Prepare environment.
 # Create needed folders
@@ -42,4 +43,4 @@ COPY --chown=1000:1000 target/dta-backend.jar app.jar
 
 USER 1000
 
-ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]
+ENTRYPOINT ["java","-Djava.security.egd=file:/dev/./urandom","-jar","/app.jar"]
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