public Procedure(String schema, String name, List<Argument> arguments, MethodHandle methodHandle) { this.schema = checkNotNullOrEmpty(schema, "schema").toLowerCase(ENGLISH); this.name = checkNotNullOrEmpty(name, "name").toLowerCase(ENGLISH); this.arguments = unmodifiableList(new ArrayList<>(arguments)); this.methodHandle = requireNonNull(methodHandle, "methodHandle is null"); Set<String> names = new HashSet<>(); for (Argument argument : arguments) { checkArgument(names.add(argument.getName()), "Duplicate argument name: " + argument.getName()); } checkArgument(!methodHandle.isVarargsCollector(), "Method must have fixed arity"); checkArgument(methodHandle.type().returnType() == void.class, "Method must return void"); long parameterCount = methodHandle.type().parameterList().stream() .filter(type -> !ConnectorSession.class.isAssignableFrom(type)) .count(); checkArgument(parameterCount == arguments.size(), "Method parameter count must match arguments"); }