private com.google.protobuf.RepeatedFieldBuilderV3<
            com.google.cloud.vertexai.api.Part,
            com.google.cloud.vertexai.api.Part.Builder,
            com.google.cloud.vertexai.api.PartOrBuilder>
        getPartsFieldBuilder() {
      if (partsBuilder_ == null) {
        partsBuilder_ =
            new com.google.protobuf.RepeatedFieldBuilderV3<
                com.google.cloud.vertexai.api.Part,
                com.google.cloud.vertexai.api.Part.Builder,
                com.google.cloud.vertexai.api.PartOrBuilder>(
                parts_, ((bitField0_ & 0x00000002) != 0), getParentForChildren(), isClean());
        parts_ = null;
      }
      return partsBuilder_;
    }
<pre>
Required. Ordered `Parts` that constitute a single message. Parts may have
different IANA MIME types.
</pre>

<code>
repeated .google.cloud.vertexai.v1.Part parts = 2 [(.google.api.field_behavior) = REQUIRED];
</code>
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/Content.java