public Builder setSource(String source) {
      this.source = source;
      return this;
    }
Builder for
projects/{project}/locations/{location}/sources/{source}/migratingVms/{migrating_vm}/cloneJobs/{clone_job}.
java-vmmigration/proto-google-cloud-vmmigration-v1/src/main/java/com/google/cloud/vmmigration/v1/CloneJobName.java