code: private static final <T extends Tuple, K> TypeComparator<T> createLeadingFieldComparator(boolean ascending, TypeInformation<?> info) {
  		if (!(info.isKeyType() && info instanceof AtomicType)) {
  			throw new IllegalArgumentException("The field at position 0 (" + info + ") is no atomic key type.");
  		}
  		
  		@SuppressWarnings("unchecked")
  		AtomicType<K> typedInfo = (AtomicType<K>) info;
  		return new TupleLeadingFieldComparator<T, K>(typedInfo.createComparator(ascending));
  	}
docs: END_OF_TUPLE_DEPENDENT_CODE