code: package org.optsol.project_scheduling.mrcpsp.ctab.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.HashSet;
  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.ctab.variables.DecisionVars_Ctab;
  import org.optsol.project_scheduling.utils.Precedence;
  
  public class CTAB_c_Precedences<CONST extends IConstants_P & IConstants_p_im>
      extends AbstractOrtoolsConstraintManager<CONST> {
  
    public CTAB_c_Precedences() {
      super("i", "j");
    }
  
    @Override
    protected Collection<ConstraintKey> createKeys(CONST constants) {
      //generate all indexes of constraint group:
      HashSet<ConstraintKey> indexes = new HashSet<>();
      for (Precedence prec : constants.get_P()) {
        indexes.add(new ConstraintKey(prec.get_i(), prec.get_j()));
      }
      return indexes;
    }
  
    @Override
    protected void configureConstraint(
        MPConstraint constraint,
        CONST constants,
        AbstractVariableManager<MPSolver, MPVariable> variables,
        ConstraintKey index) throws Exception {
  
      int i = index.get("i");
      int j = index.get("j");
  
      constraint.setUb(0);
  
      constraint.setCoefficient(variables.getVar(DecisionVars_Ctab.s, i), 1);
      constraint.setCoefficient(variables.getVar(DecisionVars_Ctab.s, j), -1);
  
      for (int m : constants.get_M_i(i)) {
        constraint.setCoefficient(variables.getVar(DecisionVars_Ctab.x, i, m),
            constants.get_p_im(i, m));
      }
    }
  }
  