Program: 12042
Project: 12042
Buggy source:
/** 
 * trim inside of the second level braces.
 * @param source
 * @return
 */
public static String trimInsideOfBraces(String source){
  int len=source.length();
  boolean isInsideOfTargetClass=false;
  boolean isInsideOfFirstLevel=false;
  boolean isInsideOfSecondLevel=false;
  Stack<Character> braceStack=new Stack<Character>();
  StringBuilder sb=new StringBuilder();
  for (int i=0; i < len; i++) {
    if (!isInsideOfTargetClass) {
      sb.append(source.charAt(i));
      if (i >= 6 && source.charAt(i - 6) == ' ' && source.charAt(i - 5) == 'c' && source.charAt(i - 4) == 'l' && source.charAt(i - 3) == 'a' && source.charAt(i - 2) == 's' && source.charAt(i - 1) == 's' && source.charAt(i) == ' ') {
        isInsideOfTargetClass=true;
      }
      continue;
    }
    if (!isInsideOfFirstLevel) {
      sb.append(source.charAt(i));
      if (source.charAt(i) == '{') {
        isInsideOfFirstLevel=true;
      }
      continue;
    }
    if (!isInsideOfSecondLevel) {
      sb.append(source.charAt(i));
    }
    if (source.charAt(i) == '{') {
      isInsideOfSecondLevel=true;
      braceStack.push(source.charAt(i));
    }
    if (!braceStack.empty() && source.charAt(i) == '}') {
      braceStack.pop();
      if (braceStack.empty()) {
        sb.append(source.charAt(i));
      }
    }
    if (braceStack.empty()) {
      isInsideOfSecondLevel=false;
    }
  }
  return sb.toString();
}

Fixed version (ground truth):
/** 
 * trim inside of the second level braces.
 * @param source
 * @return
 */
public static String trimInsideOfBraces(String source){
  int len=source.length();
  boolean isInsideOfString=false;
  boolean isInsideOfChar=false;
  boolean isInsideOfTargetClass=false;
  boolean isInsideOfFirstLevel=false;
  boolean isInsideOfSecondLevel=false;
  Stack<Character> braceStack=new Stack<Character>();
  StringBuilder sb=new StringBuilder();
  for (int i=0; i < len; i++) {
    char current=source.charAt(i);
    if (i > 0) {
      if (current == '"' && source.charAt(i - 1) != '\\') {
        isInsideOfString=(isInsideOfString) ? false : true;
      }
      if (current == '\'' && source.charAt(i - 1) != '\\') {
        isInsideOfChar=(isInsideOfChar) ? false : true;
      }
    }
    if (isInsideOfChar || isInsideOfString) {
      System.out.print("String_Node_Str" + current);
      continue;
    }
    System.out.print(current);
    if (!isInsideOfTargetClass) {
      sb.append(current);
      if (i >= 6 && source.charAt(i - 6) == ' ' && source.charAt(i - 5) == 'c' && source.charAt(i - 4) == 'l' && source.charAt(i - 3) == 'a' && source.charAt(i - 2) == 's' && source.charAt(i - 1) == 's' && current == ' ') {
        isInsideOfTargetClass=true;
      }
      continue;
    }
    if (!isInsideOfFirstLevel) {
      sb.append(current);
      if (current == '{') {
        isInsideOfFirstLevel=true;
      }
      continue;
    }
    if (!isInsideOfSecondLevel) {
      sb.append(current);
    }
    if (current == '{') {
      isInsideOfSecondLevel=true;
      braceStack.push(current);
    }
    if (!braceStack.empty() && current == '}') {
      braceStack.pop();
      if (braceStack.empty()) {
        sb.append(current);
      }
    }
    if (braceStack.empty()) {
      isInsideOfSecondLevel=false;
    }
  }
  return sb.toString();
}