docs: private boolean validateKeyTypeIsHashable(TypeInformation<?> type) {
  		try {
  			return (type instanceof PojoTypeInfo)
  					? !type.getTypeClass().getMethod("hashCode").getDeclaringClass().equals(Object.class)
  					: !(type instanceof PrimitiveArrayTypeInfo || type instanceof BasicArrayTypeInfo || type instanceof ObjectArrayTypeInfo);
  		} catch (NoSuchMethodException ignored) {
  			// this should never happen as we are just searching for the hashCode() method.
  		}
  		return false;
  	}