You can make your Dockerfile this way:

FROM maven:3.8.4-openjdk-11-slim AS build

WORKDIR /app

COPY ./pom.xml .

COPY ./src ./src

RUN mvn dependency:go-offline
RUN mvn package -DskipTests -Dmaven.test.skip=true

FROM openjdk:11-jre-slim

RUN apt-get update && apt-get install -y tini && \
    apt-get clean && \
    rm -rf /var/lib/apt/lists/*

WORKDIR /app

COPY --from=build /app/target/*.jar /app/app.jar

EXPOSE 8080

ENTRYPOINT ["/usr/bin/tini", "--"]
CMD ["java", "-jar", "/app/app.jar"]

This video explains how to do it: https://youtu.be/17lOfTfAHsk?si=KDsp3ygQT2eUnVi7