check why this does not work because of the List<V> generic type

check why this does not work because of the List generic type

public void open(ExecutionContext executionContext) {

context = executionContext.getBroadcast("context").iterator().next();

https://github.com/apache/incubator-wayang/blob/d75a5723989928ac2e633d76bf665b2a5cb3eaf1/wayang-ml4all/src/main/java/org/apache/wayang/ml4all/abstraction/plan/wrappers/AssignWrapper.java#L26

```java

/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package org.apache.wayang.ml4all.abstraction.plan.wrappers;

import org.apache.wayang.ml4all.abstraction.api.Update;
import org.apache.wayang.ml4all.abstraction.plan.ML4allGlobalVars;

import java.util.List;

public class AssignWrapper extends LogicalOperatorWrapperWithContext> { //TODO:check why this does not work because of the List generic type

Update logOp;

public AssignWrapper(Update logOp) {
this.logOp = logOp;
}

@Override
public ML4allGlobalVars apply(List o) {
ML4allGlobalVars newContext = context.clone();
return this.logOp.assign(o, newContext);
}

@Override
public void initialise() {

}

// @Override
// public void open(ExecutionContext executionContext) {
// context = executionContext.getBroadcast("context").iterator().next();
//
// }
}

```

c3d0a623a7d8e7bac13e2adf6316762638dd2b33

Start with wayang-ml4all/src/main/java/org/apache/wayang/ml4all/abstraction/plan/wrappers/AssignWrapper.java, especially its List declaration, Update field, constructor, and commented open method. Trace the related LogicalOperatorWrapperWithContext and Update types to determine why the generic List type fails. Done means the issue is understood and the project builds with a correct, type-safe AssignWrapper implementation.

Written by the indexing model from the issue text.