@java.lang.Override
  public final boolean isInitialized() {
    byte isInitialized = memoizedIsInitialized;
    if (isInitialized == 1) return true;
    if (isInitialized == 0) return false;

    memoizedIsInitialized = 1;
    return true;
  }
<pre>
The filter applied to the returned corpora list.
Only the following restrictions are supported:
`type=&lt;Corpus.Type&gt;`,
`type!=&lt;Corpus.Type&gt;`.
</pre>

<code>string filter = 5;</code>

@return The bytes for filter.
java-visionai/proto-google-cloud-visionai-v1/src/main/java/com/google/cloud/visionai/v1/ListCorporaRequest.java