Bug 127861 [DataBinding] Mark API provisional
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/converterfunction/ConversionFunctionRegistry.java
* Returns the set of converters to convert from a specified source class
     */
    private static HashMap getSourceClassConverters(Class sourceClass) {
        HashMap result = (HashMap) converterFunctions.get(sourceClass);
        
        if (result == null) {
            result = new HashMap();
            converterFunctions.put(sourceClass, result);
        }
        
        return result;
    }
    
    /**
     * Associate a particular converter with a particular pair of classes.
     * 
     * @param sourceClass The type to convert from
     * @param destClass The type to convert to
     * @param conversionFunction The IConversionFunction
     */
    public static void associate(Class sourceClass, Class destClass, IConversionFunction conversionFunction) {
        HashMap sourceClassConverters = getSourceClassConverters(sourceClass);
        sourceClassConverters.put(destClass, conversionFunction);
    }
    
    /**
     * Return an IConversionFunction for a specific class2class conversion.
     * 
     * @param sourceClass The source class
     * @param destClass The destination class