public Builder setUpdateMask(com.google.protobuf.FieldMask.Builder builderForValue) {
      if (updateMaskBuilder_ == null) {
        updateMask_ = builderForValue.build();
      } else {
        updateMaskBuilder_.setMessage(builderForValue.build());
      }
      bitField0_ |= 0x00000001;
      onChanged();
      return this;
    }
<pre>
Field mask is used to specify the fields to be overwritten in the
MigratingVm resource by the update.
The fields specified in the update_mask are relative to the resource, not
the full request. A field will be overwritten if it is in the mask. If the
user does not provide a mask then all fields will be overwritten.
</pre>

<code>.google.protobuf.FieldMask update_mask = 1;</code>
java-vmmigration/proto-google-cloud-vmmigration-v1/src/main/java/com/google/cloud/vmmigration/v1/UpdateMigratingVmRequest.java