private void ensureEnumIsMutable() {
      if (!enum_.isModifiable()) {
        enum_ = new com.google.protobuf.LazyStringArrayList(enum_);
      }
      bitField0_ |= 0x00000200;
    }
<pre>
Optional. Maximum number of the elements for Type.ARRAY.
</pre>

<code>int64 max_items = 22 [(.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/Schema.java