public ContainerBuildPlan toContainerBuildPlan() {
    return containerBuildPlanBuilder.build();
  }
Internal method. API end users should not use it.

<p>Converts to {@link ContainerBuildPlan}. Note that not all values that this class holds can
be described by a build plan, such as {@link CredentialRetriever}s for {@link RegistryImage},
{@link DockerClient} for {@link DockerDaemonImage}, and output path for {@link TarImage}.

@return {@link ContainerBuildPlan}
jib-core/src/main/java/com/google/cloud/tools/jib/api/JibContainerBuilder.java