code: package org.optsol.project_scheduling.mrcpsp.cpm.constraints;
  
  import com.google.ortools.linearsolver.MPConstraint;
  import com.google.ortools.linearsolver.MPSolver;
  import com.google.ortools.linearsolver.MPVariable;
  import java.util.Collection;
  import java.util.stream.Collectors;
  import org.optsol.jdecor.core.AbstractConstraintManager;
  import org.optsol.jdecor.core.AbstractVariableManager;
  import org.optsol.jdecor.ortools.AbstractOrtoolsConstraintManager;
  import org.optsol.project_scheduling.mrcpsp.constants.sub.IConstants_P;
  import org.optsol.project_scheduling.mrcpsp.constants.sub.IConstants_p_im;
  import org.optsol.project_scheduling.mrcpsp.cpm.variables.DecisionVars_Cpm_Bwd;
  
  public class CPM_Bwd_b_Precedences<CONST extends IConstants_P & IConstants_p_im>
      extends AbstractOrtoolsConstraintManager<CONST> {
  
    public CPM_Bwd_b_Precedences() {
      super("i", "j");
    }
  
    @Override
    protected Collection<AbstractConstraintManager<
        MPSolver, CONST, MPVariable, MPConstraint>.ConstraintKey> createKeys(
        CONST constants) {
  
      return
          constants.get_P()
              .stream()
              .map(precedence -> new ConstraintKey(precedence.get_i(), precedence.get_j()))
              .collect(Collectors.toSet());
    }
  
    @Override
    protected void configureConstraint(
        MPConstraint constraint,
        CONST constants,
        AbstractVariableManager<MPSolver, MPVariable> variables,
        AbstractConstraintManager<MPSolver, CONST, MPVariable, MPConstraint>.ConstraintKey index)
        throws Exception {
  
      int i = index.get("i");
      int j = index.get("j");
  
      constraint.setLb(constants.get_p_i_min(j));
  
      constraint.setCoefficient(
          variables.getVar(DecisionVars_Cpm_Bwd.c, j),
          1.);
  
      constraint.setCoefficient(
          variables.getVar(DecisionVars_Cpm_Bwd.c, i),
          -1.);
    }
  }
  