Build Open Liberty container image w/ multi-stage build

Dockerfile_openliberty

# Build stage
FROM maven:3.6-openjdk-11 AS builder
WORKDIR /app
COPY . /app
RUN mvn clean package

# Runtime stage
FROM openjdk:11
WORKDIR /app
COPY --from=builder /app/target/sample-app.jar .

# HTTP
EXPOSE 9080
# HTTPS
EXPOSE 9443

CMD ["java", "-jar", "sample-app.jar"]