private com.google.protobuf.SingleFieldBuilderV3<
              com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                  .GceRegionalPersistentDisk,
              com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                  .GceRegionalPersistentDisk.Builder,
              com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                  .GceRegionalPersistentDiskOrBuilder>
          getGcePdFieldBuilder() {
        if (gcePdBuilder_ == null) {
          if (!(directoryTypeCase_ == 2)) {
            directoryType_ =
                com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                    .GceRegionalPersistentDisk.getDefaultInstance();
          }
          gcePdBuilder_ =
              new com.google.protobuf.SingleFieldBuilderV3<
                  com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                      .GceRegionalPersistentDisk,
                  com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                      .GceRegionalPersistentDisk.Builder,
                  com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                      .GceRegionalPersistentDiskOrBuilder>(
                  (com.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory
                          .GceRegionalPersistentDisk)
                      directoryType_,
                  getParentForChildren(),
                  isClean());
          directoryType_ = null;
        }
        directoryTypeCase_ = 2;
        onChanged();
        return gcePdBuilder_;
      }
<pre>
A PersistentDirectory backed by a Compute Engine persistent disk.
</pre>

<code>
.google.cloud.workstations.v1.WorkstationConfig.PersistentDirectory.GceRegionalPersistentDisk gce_pd = 2;
</code>
java-workstations/proto-google-cloud-workstations-v1/src/main/java/com/google/cloud/workstations/v1/WorkstationConfig.java