code: public String rowRemove(String key) {
          String resolvedKey = resolveRowKey(key);
          rowMapCache.clear();
          return rowMap.remove(resolvedKey);
      }
docs: Removes the row value mapping for this key from this map if it is present.<p>
  
  Returns the value to which the map previously associated the key, or {@code null} if the map
  contained no mapping for this key. The map will not contain a String mapping for the
  specified key once the call returns.
  
  @param key key whose mapping is to be removed from the map.
  @return previous value associated with specified key, or {@code null} if there was no mapping
  for key.
  
  @throws NullPointerException if {@code key} is {@code null}.
  
  @see Map#remove(Object)