Bug 126414 [Commands] handlers: Provide help context ids
For commands and handlers to replace actions, they need to be capable of providing help context identifiers. For an example, see OpenResourceHandler in org.eclipse.ui.ide. This help context id will need to be definable through XML and through code.
bundles/org.eclipse.core.commands/src/org/eclipse/core/commands/Command.java
return category;
	}
	/**
	 * Returns the parameter with the provided id or <code>null</code> if this
	 * command does not have a parameter with the id.
	 * 
	 * @param parameterId
	 *            The id of the parameter to retrieve.
	 * @return The parameter with the provided id or <code>null</code> if this
	 *         command does not have a parameter with the id.
	 * @throws NotDefinedException
	 *             If the handle is not currently defined.
	 * @since 3.2
	 */
	public final IParameter getParameter(final String parameterId)
			throws NotDefinedException {
		if (!isDefined()) {
			throw new NotDefinedException(
					"Cannot get a parameter from an undefined command"); 
		}
		if (parameters == null) {
			return null;
		}
		for (int i = 0; i < parameters.length; i++) {
			final IParameter parameter = parameters[i];
			if (parameter.getId().equals(parameterId)) {
				return parameter;
			}
		}
		return null;