code: final Node<K,V> getNode(int hash, Object key) {
          Node<K,V>[] tab; Node<K,V> first, e; int n; K k;
          if ((tab = table) != null && (n = tab.length) > 0 &&
              (first = tab[(n - 1) & hash]) != null) {
              if (first.hash == hash && // always check first node
                  ((k = first.key) == key || (key != null && key.equals(k))))
                  return first;
              if ((e = first.next) != null) {
                  if (first instanceof TreeNode)
                      return ((TreeNode<K,V>)first).getTreeNode(hash, key);
                  do {
                      if (e.hash == hash &&
                          ((k = e.key) == key || (key != null && key.equals(k))))
                          return e;
                  } while ((e = e.next) != null);
              }
          }
          return null;
      }
docs: Implements Map.get and related methods
  
  @param hash hash for key
  @param key the key
  @return the node, or null if none