Program: 88686
Project: 88686
Buggy source:
public static String toString(Object o){
  if (o instanceof Collection) {
    Collection<?> c=(Collection<?>)o;
    int count=0;
    while (c.size() == 1 && c != c.iterator().next() && count++ < 5) {
      o=c.iterator().next();
      if (o instanceof Collection) {
        c=(Collection<?>)o;
      }
    }
    if (c == o && c.size() != 1) {
      StringBuffer sb=new StringBuffer();
      sb.append("String_Node_Str");
      boolean first=true;
      for (      Object oo : c) {
        if (first)         first=false;
 else         sb.append("String_Node_Str");
        sb.append(toString(oo));
      }
      sb.append("String_Node_Str");
      return sb.toString();
    }
  }
  String result=null;
  String name=getName(o);
  if (Utils2.isNullOrEmpty(name))   name="String_Node_Str";
 else   name=name + "String_Node_Str";
  if (o instanceof Element) {
    Element e=(Element)o;
    String repText=e.get_representationText();
    if (Utils2.isNullOrEmpty(repText))     repText="String_Node_Str";
 else     repText="String_Node_Str" + repText;
    result=name + (Debug.isOn() ? e.getID() : "String_Node_Str") + repText;
    if (Debug.isOn()) {
      Debug.out("String_Node_Str");
    }
    return result.replaceFirst("String_Node_Str","String_Node_Str");
  }
  if (Utils2.isNullOrEmpty(name)) {
    result=o.toString();
  }
 else {
    result=name + getTypeNames(o);
  }
  return result;
}

Fixed version (ground truth):
public static String toString(Object o){
  if (o == null)   return "String_Node_Str";
  if (o instanceof Collection) {
    Collection<?> c=(Collection<?>)o;
    int count=0;
    while (c.size() == 1 && c != c.iterator().next() && count++ < 5) {
      o=c.iterator().next();
      if (o instanceof Collection) {
        c=(Collection<?>)o;
      }
    }
    if (c == o && c.size() != 1) {
      StringBuffer sb=new StringBuffer();
      sb.append("String_Node_Str");
      boolean first=true;
      for (      Object oo : c) {
        if (first)         first=false;
 else         sb.append("String_Node_Str");
        sb.append(toString(oo));
      }
      sb.append("String_Node_Str");
      return sb.toString();
    }
  }
 else   if (o.getClass().isArray()) {
    Object[] arr=(Object[])o;
    if (arr.length == 1)     return toString(arr[0]);
    return toString(Arrays.asList(arr));
  }
  String result=null;
  String name=getName(o);
  if (Utils2.isNullOrEmpty(name))   name="String_Node_Str";
 else   name=name + "String_Node_Str";
  if (o instanceof Element) {
    Element e=(Element)o;
    String repText=e.get_representationText();
    if (Utils2.isNullOrEmpty(repText))     repText="String_Node_Str";
 else     repText="String_Node_Str" + repText;
    result=name + (Debug.isOn() ? e.getID() : "String_Node_Str") + repText;
    result=result.replaceFirst("String_Node_Str","String_Node_Str");
    result=result.trim().replaceAll("String_Node_Str","String_Node_Str");
    result=result.trim().replaceAll("String_Node_Str","String_Node_Str");
    return result;
  }
  if (Utils2.isNullOrEmpty(name)) {
    result=o.toString();
  }
 else {
    result=name + getTypeNames(o);
  }
  result=result.trim().replaceAll("String_Node_Str","String_Node_Str");
  result=result.trim().replaceAll("String_Node_Str","String_Node_Str");
  return result;
}