public Builder clearUsage() {
      usage_ = getDefaultInstance().getUsage();
      bitField0_ = (bitField0_ & ~0x00000008);
      onChanged();
      return this;
    }
<pre>
Output only. Usage of the sentence pair. Options are TRAIN|VALIDATION|TEST.
</pre>

<code>string usage = 4 [(.google.api.field_behavior) = OUTPUT_ONLY];</code>

@return This builder for chaining.
java-translate/proto-google-cloud-translate-v3/src/main/java/com/google/cloud/translate/v3/Example.java