public com.google.protobuf.FieldMask getUpdateMask() {
      if (updateMaskBuilder_ == null) {
        return updateMask_ == null
            ? com.google.protobuf.FieldMask.getDefaultInstance()
            : updateMask_;
      } else {
        return updateMaskBuilder_.getMessage();
      }
    }
<pre>
Required. Mask specifying which fields in the workstation configuration
should be updated.
</pre>

<code>.google.protobuf.FieldMask update_mask = 2 [(.google.api.field_behavior) = REQUIRED];
</code>

@return The updateMask.
java-workstations/proto-google-cloud-workstations-v1beta/src/main/java/com/google/cloud/workstations/v1beta/UpdateWorkstationConfigRequest.java