@Input
  @Optional
  public Property<String> getFilesModificationTime() {
    String property = System.getProperty(PropertyNames.CONTAINER_FILES_MODIFICATION_TIME);
    if (property != null && !property.equals(filesModificationTime.get())) {
      filesModificationTime.set(property);
    }
    return filesModificationTime;
  }
A bean that configures properties of the container run from the image. This is configurable with
Groovy closures and can be validated when used as a task input.
jib-gradle-plugin/src/main/java/com/google/cloud/tools/jib/gradle/ContainerParameters.java