Allow changing existing jib images without the "package" maven goal having run

[wleese]

Environment:

• Jib version: 3.4.3
• Build tool: Maven 3.9.7
• OS: Linux

Description of the issue:

While getting CDS to work with containerizingMode packaged & jib works, there's a task where I simply want to add a file to an existing Jib container.

When I simply run:

      ./mvnw -Drevision="${VERSION}" \
        -Djib.to.image="${DOCKER_IMAGE}:${VERSION}" \
        -Djib.from.image="${DOCKER_IMAGE}:${VERSION}" \
        -Djib.extraDirectories.paths=./cds_output \
        -Djib.container.jvmFlags=-XX:SharedArchiveFile=/application.jsa \ # <3>
        jib:build

I get the error:

Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.4.3:build (default-cli) on project cdstestng-app: Obtaining project build output files failed; make sure you have packaged your project before trying to build the image. (Did you accidentally run "mvn clean jib:build" instead of "mvn clean package jib:build"?):

This makes perfect sense in the traditional setup of building an application and then containerizing, but because I'm using Jib to perform 3 actions (build, run to generate the cds data, insert the cds data into previously built image), I run into having to have the build artifacts from the first action, despite there not being a strict need for these files (as far as I'm aware) because we already have access to the container image.

One can run into this issue when there's a CICD pipeline where these actions are split into jobs, each with their own clean environment. Because of this issue, I have to explicitly configure the pipeline to bring the artifacts from the build action (job) to the final action (job) just to get Jib to run.

Expected behavior:

It would be great for the CDS use case if Jib could modify an existing image, without an artificial (?) requirement on a previous maven phase having run.