code: @SuppressWarnings({ "unchecked", "rawtypes" })
  	public static Class<? extends Operator> getContractClass(final Class<?> stubClass) {
  		if (stubClass == null) {
  			return null;
  		}
  		final Class<?> contract = STUB_CONTRACTS.get(stubClass);
  		if (contract != null) {
  			return (Class<? extends Operator<?>>) contract;
  		}
  		Iterator<Entry<Class<?>, Class<? extends Operator>>> stubContracts = STUB_CONTRACTS.entrySet().iterator();
  		while (stubContracts.hasNext()) {
  			Map.Entry<Class<?>, Class<? extends Operator>> entry = stubContracts.next();
  			if (entry.getKey().isAssignableFrom(stubClass)) {
  				return entry.getValue();
  			}
  		}
  		return null;
  
  	}
docs: Returns the associated {@link Operator} type for the given {@link eu.stratosphere.api.common.functions.Function} class.
  
  @param stubClass
  the stub class
  @return the associated Operator type