Program: 42179
Project: 42179
Buggy source:
@Override public ICharPred MkAnd(ICharPred u1,ICharPred u2){
  if (u1 instanceof CharPred) {
    CharPred u1c=(CharPred)u1;
    if (u2 instanceof CharPred) {
      CharPred u2c=(CharPred)u2;
      if (u1c.isReturn()) {
        if (u2c.isReturn()) {
          CharPred cp=usolver.MkAnd(u1c,u2c);
          cp.setAsReturn();
          return cp;
        }
 else {
          throw new NotImplementedException("String_Node_Str");
        }
      }
 else {
        if (u2c.isReturn()) {
          ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
          newUneq.add(new Pair<CharPred,CharPred>(u1c,u2c));
          return new BinaryCharPred(usolver.MkAnd(u1c,u2c),newUneq);
        }
 else {
          return usolver.MkAnd(u1c,u2c);
        }
      }
    }
 else {
      BinaryCharPred u2c=(BinaryCharPred)u2;
      if (u1c.isReturn()) {
        CharPred newEq=usolver.MkAnd(u1c,u2c.equals);
        ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
        for (        Pair<CharPred,CharPred> pair : u2c.notEqual) {
          CharPred conj=usolver.MkAnd(pair.second,u1c);
          if (usolver.IsSatisfiable(conj))           newUneq.add(new Pair<CharPred,CharPred>(pair.first,conj));
        }
        BinaryCharPred pp=new BinaryCharPred(newEq,newUneq);
        return pp;
      }
 else {
        CharPred newEq=usolver.MkAnd(u1c,u2c.equals);
        ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
        for (        Pair<CharPred,CharPred> pair : u2c.notEqual) {
          CharPred conj=usolver.MkAnd(pair.first,u1c);
          if (usolver.IsSatisfiable(conj))           newUneq.add(new Pair<CharPred,CharPred>(conj,pair.second));
        }
        BinaryCharPred pp=new BinaryCharPred(newEq,newUneq);
        return pp;
      }
    }
  }
 else {
    BinaryCharPred u1c=(BinaryCharPred)u1;
    if (u2 instanceof CharPred) {
      CharPred u2c=(CharPred)u2;
      if (u2c.isReturn()) {
        return MkAnd(u2,u1);
      }
 else {
        throw new NotImplementedException("String_Node_Str");
      }
    }
 else {
      BinaryCharPred u2c=(BinaryCharPred)u2;
      CharPred newEq=usolver.MkAnd(u1c.equals,u2c.equals);
      ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
      for (      Pair<CharPred,CharPred> pair1 : u1c.notEqual) {
        for (        Pair<CharPred,CharPred> pair2 : u2c.notEqual) {
          CharPred newFirst=usolver.MkAnd(pair1.first,pair2.first);
          if (usolver.IsSatisfiable(newFirst)) {
            CharPred newSecond=usolver.MkAnd(pair1.second,pair2.second);
            if (usolver.IsSatisfiable(newFirst))             newUneq.add(new Pair<CharPred,CharPred>(newFirst,newSecond));
          }
        }
      }
      return new BinaryCharPred(newEq,newUneq);
    }
  }
}

Fixed version (ground truth):
@Override public ICharPred MkAnd(ICharPred u1,ICharPred u2){
  if (u1 instanceof CharPred) {
    CharPred u1c=(CharPred)u1;
    if (u2 instanceof CharPred) {
      CharPred u2c=(CharPred)u2;
      if (u1c.isReturn()) {
        if (u2c.isReturn()) {
          CharPred cp=usolver.MkAnd(u1c,u2c);
          cp.setAsReturn();
          return cp;
        }
 else {
          throw new NotImplementedException("String_Node_Str");
        }
      }
 else {
        if (u2c.isReturn()) {
          ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
          newUneq.add(new Pair<CharPred,CharPred>(u1c,u2c));
          return new BinaryCharPred(usolver.MkAnd(u1c,u2c),newUneq);
        }
 else {
          return usolver.MkAnd(u1c,u2c);
        }
      }
    }
 else {
      BinaryCharPred u2c=(BinaryCharPred)u2;
      if (u1c.isReturn()) {
        CharPred newEq=usolver.MkAnd(u1c,u2c.equals);
        ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
        for (        Pair<CharPred,CharPred> pair : u2c.notEqual) {
          CharPred conj=usolver.MkAnd(pair.second,u1c);
          if (usolver.IsSatisfiable(conj))           newUneq.add(new Pair<CharPred,CharPred>(pair.first,conj));
        }
        BinaryCharPred pp=new BinaryCharPred(newEq,newUneq);
        return pp;
      }
 else {
        CharPred newEq=usolver.MkAnd(u1c,u2c.equals);
        ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
        for (        Pair<CharPred,CharPred> pair : u2c.notEqual) {
          CharPred conj=usolver.MkAnd(pair.first,u1c);
          if (usolver.IsSatisfiable(conj))           newUneq.add(new Pair<CharPred,CharPred>(conj,pair.second));
        }
        BinaryCharPred pp=new BinaryCharPred(newEq,newUneq);
        return pp;
      }
    }
  }
 else {
    BinaryCharPred u1c=(BinaryCharPred)u1;
    if (u2 instanceof CharPred) {
      CharPred u2c=(CharPred)u2;
      if (u2c.isReturn()) {
        return MkAnd(u2,u1);
      }
 else {
        throw new NotImplementedException("String_Node_Str");
      }
    }
 else {
      BinaryCharPred u2c=(BinaryCharPred)u2;
      CharPred newEq=usolver.MkAnd(u1c.equals,u2c.equals);
      ArrayList<Pair<CharPred,CharPred>> newUneq=new ArrayList<>();
      for (      Pair<CharPred,CharPred> pair1 : u1c.notEqual) {
        for (        Pair<CharPred,CharPred> pair2 : u2c.notEqual) {
          CharPred newFirst=usolver.MkAnd(pair1.first,pair2.first);
          if (usolver.IsSatisfiable(newFirst)) {
            CharPred newSecond=usolver.MkAnd(pair1.second,pair2.second);
            if (usolver.IsSatisfiable(newSecond))             newUneq.add(new Pair<CharPred,CharPred>(newFirst,newSecond));
          }
        }
      }
      return new BinaryCharPred(newEq,newUneq);
    }
  }
}