@java.lang.Override
    public boolean getNullable() {
      return nullable_;
    }
<pre>
Optional. Indicates if the value may be null.
</pre>

<code>bool nullable = 6 [(.google.api.field_behavior) = OPTIONAL];</code>

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