public Builder clearSourceSentence() {
      sourceSentence_ = getDefaultInstance().getSourceSentence();
      bitField0_ = (bitField0_ & ~0x00000002);
      onChanged();
      return this;
    }
<pre>
Required. The source sentence.
</pre>

<code>string source_sentence = 2 [(.google.api.field_behavior) = REQUIRED];</code>

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