Bug 125420 [Commands] parameters: allow commands to specify return type
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
* @throws NotDefinedException
	 *             If the handle is not currently defined.
	 */
	public final IParameter[] getParameters() throws NotDefinedException {
		if (!isDefined()) {
			throw new NotDefinedException(
					"Cannot get the parameters from an undefined command"); 
		}
		if ((parameters == null) || (parameters.length == 0)) {
			return null;
		}
		final IParameter[] returnValue = new IParameter[parameters.length];
		System.arraycopy(parameters, 0, returnValue, 0, parameters.length);
		return returnValue;
	}
	/**
	 * Returns the {@link ParameterType} for the parameter with the provided id
	 * or <code>null</code> if this command does not have a parameter type
	 * with the id.
	 * 
	 * @param parameterId
	 *            The id of the parameter to retrieve the {@link ParameterType}
	 *            of.
	 * @return The {@link ParameterType} for the parameter with the provided id
	 *         or <code>null</code> if this command does not have a parameter
	 *         type with the provided id.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 * @since 3.2
	 */