@java.lang.Override
    public boolean hasVectorDistanceThreshold() {
      return vectorDbThresholdCase_ == 3;
    }
<pre>
Optional. Only returns contexts with vector distance smaller than the
threshold.
</pre>

<code>double vector_distance_threshold = 3 [(.google.api.field_behavior) = OPTIONAL];</code>

@return Whether the vectorDistanceThreshold field is set.
java-vertexai/proto-google-cloud-vertexai-v1/src/main/java/com/google/cloud/vertexai/api/RagRetrievalConfig.java