onReceiveContent
@Nullable
Implements the default behavior for receiving content, which coerces all content to text and inserts into the view.
IMPORTANT: This method is provided to enable custom widgets that extend this class to customize the default behavior for receiving content. Apps wishing to provide custom behavior for receiving content should not override this method, but rather should set a listener via setOnReceiveContentListener. App code wishing to inject content into this view should not call this method directly, but rather should invoke performReceiveContent.
Return
The portion of the passed-in content that was not handled (may be all, some, or none of the passed-in content).
Parameters
payload
The content to insert and related metadata.