private com.google.protobuf.MapField<java.lang.String, java.lang.String>
        internalGetMutableAnnotations() {
      if (annotations_ == null) {
        annotations_ =
            com.google.protobuf.MapField.newMapField(AnnotationsDefaultEntryHolder.defaultEntry);
      }
      if (!annotations_.isMutable()) {
        annotations_ = annotations_.copy();
      }
      bitField0_ |= 0x00000400;
      onChanged();
      return annotations_;
    }
<pre>
Output only. The time at which this resource will be purged.
This field is not used.
</pre>

<code>
.google.protobuf.Timestamp expire_time = 12 [(.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-speech/proto-google-cloud-speech-v1p1beta1/src/main/java/com/google/cloud/speech/v1p1beta1/CustomClass.java