code: public String setParameter(String name, String value) {
  		if (value == null){
  			return removeParameter(name);
  		}
  		return parameters.put(name, value);
  	}
docs: Sets a new value to a parameter, or put a new parameter if not existant.
  If the value is <code>null</code>, the parameter is removed (same as calling the {@link #removeParameter(String)} method).
  
  @param name The name of the parameter
  @param value The value of the parameter
  @return the previous value associated with <code>name</code>, or <code>null</code> if there
  wasn't an associated value to the name.