sharedImaginaryBoundaries places the boiling-point midpoints for most cuts, because the equal-mass quantile is clamped away #4307

import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.List;
import neqsim.thermo.characterization.CharacterizationOptions;
import neqsim.thermo.characterization.PseudoComponentCombiner;
import neqsim.thermo.component.ComponentInterface;
import neqsim.thermo.system.SystemInterface;
import neqsim.thermo.system.SystemPrEos;

public class SharedBoundariesRepro {

  private static final String COMBINER = "neqsim.thermo.characterization.PseudoComponentCombiner";
  private static final String CONTRIBUTION = COMBINER + "$PseudoComponentContribution";

  /** `CharacterizeToReferenceSharedSlateTest.referenceFluid(6)`, verbatim. */
  static SystemInterface referenceFluid(int cuts) {
    SystemInterface fluid = new SystemPrEos(298.15, 60.0);
    fluid.addComponent("methane", 0.6);
    double[] molarMass = {0.080, 0.100, 0.130, 0.160, 0.200, 0.240};
    double[] density = {0.70, 0.73, 0.76, 0.79, 0.81, 0.83};
    for (int i = 0; i < cuts; i++) {
      fluid.addTBPfraction("C" + (7 + i), 0.10, molarMass[i], density[i]);
    }
    return fluid;
  }

  /** `CharacterizeToReferenceSharedSlateTest.gradedSource()`, verbatim. */
  static SystemInterface gradedSource() {
    SystemInterface fluid = new SystemPrEos(298.15, 60.0);
    fluid.addComponent("methane", 0.5);
    fluid.addTBPfraction("S1", 0.20, 0.090, 0.71);
    fluid.addTBPfraction("S2", 0.15, 0.140, 0.77);
    fluid.addTBPfraction("S3", 0.10, 0.210, 0.82);
    return fluid;
  }

  static void print(String label, SystemInterface fluid) {
    for (int i = 0; i < fluid.getNumberOfComponents(); i++) {
      ComponentInterface c = fluid.getComponent(i);
      if ((c.isIsTBPfraction() || c.isIsPlusFraction()) && c.getNumberOfmoles() > 0.0) {
        System.out.printf("%s %-8s moles=%.12f M=%.9f rho=%.9f%n", label, c.getComponentName(),
            c.getNumberOfmoles(), c.getMolarMass(), c.getNormalLiquidDensity());
      }
    }
  }

  /** The two boundary rules, on one contribution list. Both methods are private static. */
  static void boundaries(SystemInterface reference) throws Exception {
    Class<?> row = Class.forName(CONTRIBUTION);
    Constructor<?> ctor = row.getDeclaredConstructor(String.class,
        Class.forName("neqsim.thermo.component.ComponentInterface"));
    ctor.setAccessible(true);
    Field tb = row.getDeclaredField("normalBoilingPoint");
    Field mass = row.getDeclaredField("molarMass");
    tb.setAccessible(true);
    mass.setAccessible(true);

    List<Object> rows = new ArrayList<>();
    for (int i = 0; i < reference.getNumberOfComponents(); i++) {
      ComponentInterface c = reference.getComponent(i);
      if (c.isIsTBPfraction() || c.isIsPlusFraction()) {
        rows.add(ctor.newInstance(c.getComponentName(), c));
      }
    }
    // `extractComponents` sorts by sorting key before either method is handed the list.
    for (int i = 1; i < rows.size(); i++) {
      for (int j = i; j > 0; j--) {
        Object a = rows.get(j - 1);
        Object b = rows.get(j);
        double ka = ((Number) tb.get(a)).doubleValue();
        double kb = ((Number) tb.get(b)).doubleValue();
        double va = Double.isFinite(ka) && ka > 0.0 ? ka : ((Number) mass.get(a)).doubleValue();
        double vb = Double.isFinite(kb) && kb > 0.0 ? kb : ((Number) mass.get(b)).doubleValue();
        if (va <= vb) {
          break;
        }
        rows.set(j - 1, b);
        rows.set(j, a);
      }
    }

    Method withResolution = Class.forName(COMBINER)
        .getDeclaredMethod("determineReferenceEqualMassBoundaries", List.class, int.class);
    Method midpoints =
        Class.forName(COMBINER).getDeclaredMethod("determineReferenceBoundaries", List.class);
    withResolution.setAccessible(true);
    midpoints.setAccessible(true);
    @SuppressWarnings("unchecked")
    List<Double> equal = (List<Double>) withResolution.invoke(null, rows, 12);
    @SuppressWarnings("unchecked")
    List<Double> mid = (List<Double>) midpoints.invoke(null, rows);

    int same = 0;
    for (int i = 0; i < mid.size(); i++) {
      boolean identical = Math.abs(equal.get(i) - mid.get(i)) < 1e-9;
      same += identical ? 1 : 0;
      System.out.printf("cut %d: midpoint %8.3f  equal-mass %8.3f  %s%n", i, mid.get(i), equal.get(i),
          identical ? "the midpoint" : "moved");
    }
    System.out.printf("-> %d of %d cuts are the midpoint%n", same, mid.size());
  }

  public static void main(String[] args) throws Exception {
    SystemInterface reference = referenceFluid(6);
    SystemInterface source = gradedSource();

    CharacterizationOptions off = CharacterizationOptions.builder()
        .inheritReferenceProperties(false).sharedImaginaryBoundaries(false).build();
    CharacterizationOptions on = CharacterizationOptions.builder()
        .inheritReferenceProperties(false).sharedImaginaryBoundaries(true).build();
    print("shared=false", PseudoComponentCombiner.characterizeToReference(source, reference, off));
    print("shared=true ", PseudoComponentCombiner.characterizeToReference(source, reference, on));

    boundaries(referenceFluid(6));
  }
}