private com.google.protobuf.MapField<java.lang.String, java.lang.String>
        internalGetMutableMetadata() {
      if (metadata_ == null) {
        metadata_ =
            com.google.protobuf.MapField.newMapField(MetadataDefaultEntryHolder.defaultEntry);
      }
      if (!metadata_.isMutable()) {
        metadata_ = metadata_.copy();
      }
      bitField0_ |= 0x00008000;
      onChanged();
      return metadata_;
    }
<pre>
The VM Boot Option, as set in the source vm.
</pre>

<code>.google.cloud.vmmigration.v1.ComputeEngineBootOption boot_option = 15;</code>

@return This builder for chaining.
java-vmmigration/proto-google-cloud-vmmigration-v1/src/main/java/com/google/cloud/vmmigration/v1/ComputeEngineTargetDetails.java