Bug 118429 [DataBinding] Validation should use IStatus, not just Strings
In order to use data binding in Workbench or IDE dialogs and preference pages, we need validation in terms of IStatus objects. Using strings is too simplistic. For example, look at the wizard for creating a new class. You will get a warning if the class name does not start with an uppercase letter, or if you don't provide a package name, but you will still be able to click "Finish" to proceed anyway. (Note that IStatus is currently not on the classpath, we need to re-introduce the dependency on org.eclipse.equinox.common, which contains IStatus etc.)
bundles/org.eclipse.core.databinding/src/org/eclipse/core/databinding/BindSpec.java
* 
	 * @return the converter, or <code>null</code>
	 */
	public IConverter getTargetToModelConverter() {
		return (getTargetToModelConverters().length == 0) ? null
				: getTargetToModelConverters()[0];
	}
	/**
	 * Returns the converters to be used, or <code>null</code> if a default
	 * converter should be used.
	 * 
	 * @return the converters, or an empty array if none
	 */
	public IConverter[] getTargetToModelConverters() {
		return (targetToModelConverters == null) ? EMPTY_CONVERTERS
				: targetToModelConverters;
	}
	/**
	 * Returns the validator to be used, or <code>null</code> if a default
	 * validator should be used.
	 * 
	 * @return the validator, or <code>null</code>
	 */
	public IValidator getTypeConversionValidator() {
		return (getTypeConversionValidators().length == 0) ? null
				: getTypeConversionValidators()[0];
	}
	/**
	 * Returns the validators to be used, or an empty array if a default
	 * validator should be used.