question: public void addChild ( AccessibilityNodeInfo child ) { if ( mChildren == null ) { mChildren = new LinkedList < > ( ) ; } mChildren . add ( child ) ; ( ( ShadowAccessibilityNodeInfo ) ShadowExtractor . extract ( child ) ) . mParent = mRealAccessibilityNodeInfo ; }
target:  Add a child node to this one. Also initializes the parent field of the child.