code: public final ListDocumentsPagedResponse listDocuments(KnowledgeBaseName parent) {
      ListDocumentsRequest request =
          ListDocumentsRequest.newBuilder()
              .setParent(parent == null ? null : parent.toString())
              .build();
      return listDocuments(request);
    }
docs: Returns the list of all documents of the knowledge base.
  
  <p>Sample code:
  
  <pre><code>
  try (DocumentsClient documentsClient = DocumentsClient.create()) {
  KnowledgeBaseName parent = KnowledgeBaseName.of("[PROJECT]", "[KNOWLEDGE_BASE]");
  for (Document element : documentsClient.listDocuments(parent).iterateAll()) {
  // doThingsWith(element);
  }
  }
  </code></pre>
  
  @param parent Required. The knowledge base to list all documents for. Format:
  `projects/&lt;Project ID&gt;/knowledgeBases/&lt;Knowledge Base ID&gt;`.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails