@java.lang.Override
  public int getPartIndex() {
    return partIndex_;
  }
<pre>
Output only. The index of a Part object within its parent Content object.
</pre>

<code>int32 part_index = 1 [(.google.api.field_behavior) = OUTPUT_ONLY];</code>

@return The partIndex.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/Segment.java