code: package org.optsol.project_scheduling.mrcpsp.constants.shared.events;
  
  import java.util.ArrayList;
  import java.util.List;
  import org.optsol.project_scheduling.utils.ImmutableIntPair;
  
  public interface IConstants_E_squared extends IConstants_E {
  
    default List<ImmutableIntPair> get_E_squared() {
      List<ImmutableIntPair> pairs = new ArrayList<>();
      get_E().forEach(e ->
          get_E()
              .stream()
              .filter(f -> e < f)
              .map(f -> new ImmutableIntPair(e, f))
              .forEach(pairs::add));
      return pairs;
    }
  }
  