public Builder clearPresencePenalty() {
      bitField0_ = (bitField0_ & ~0x00000100);
      presencePenalty_ = 0F;
      onChanged();
      return this;
    }
<pre>
Optional. Positive penalties.
</pre>

<code>optional float presence_penalty = 8 [(.google.api.field_behavior) = OPTIONAL];</code>

@return This builder for chaining.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/GenerationConfig.java