Bug 127861 [DataBinding] Mark API provisional
bundles/org.eclipse.jface.databinding/src/org/eclipse/jface/databinding/updatables/InverseMapping.java
private Map elementsToAdapters = new HashMap();
    private Map adaptersToElementCollection = new HashMap();
    public InverseMapping() {
    }
    
    public boolean hasMapping(Object e) {
        return elementsToAdapters.containsKey(e);
    }
    
    public Object getValue(Object key) {
    	return elementsToAdapters.get(key);
    }
    
    /**
     * Adds the given mapping. Returns the set of keys that map onto the given value
     * @param key
     * @param value
     * @return