code: public static void deleteImageIfItExists( String imageId, DockerClient dockerClient ) {
  
  		if( imageId != null ) {
  			List<Image> images = dockerClient.listImagesCmd().exec();
  			if( findImageById( imageId, images ) != null )
  				dockerClient.removeImageCmd( imageId ).withForce( true ).exec();
  		}
  	}
docs: Deletes a Docker image if it exists.
  @param imageId the image ID (not null)
  @param dockerClient a Docker client