code: protected IObjectPickler getCustomPickler(Class<?> t) {
  		IObjectPickler pickler = customPicklers.get(t);
  		if(pickler!=null) {
  			return pickler;		// exact match
  		}
  
  		// check if there's a custom pickler registered for an interface or abstract base class
  		// that this object implements or inherits from.
  		for(Entry<Class<?>, IObjectPickler> x: customPicklers.entrySet()) {
  			if(x.getKey().isAssignableFrom(t)) {
  				return x.getValue();
  			}
  		}
  
  		return null;
  	}
docs: Get the custom pickler fot the given class, to be able to pickle not just built in collection types.
  A custom pickler is matched on the interface or abstract base class that the object implements or inherits from.
  @param t the class of the object to be pickled
  @return null (if no custom pickler found) or a pickler registered for this class (via {@link Pickler#registerCustomPickler})