Program: 12012
Project: 12012
Buggy source:
String addRequiredImportList(String src,Configulation config){
  String dest=src;
  String oneline=TrimFilterUtil.doAllFilters(src);
  StringBuilder importedListBuf=new StringBuilder();
  for (  String imported : targetClassMeta.importedList) {
    String newOne="String_Node_Str" + imported + "String_Node_Str";
    if (!oneline.matches(RegExp.Anything_ZeroOrMore_Min + newOne + RegExp.Anything_ZeroOrMore_Min)) {
      importedListBuf.append(newOne);
      importedListBuf.append(StringValue.CarriageReturn);
      importedListBuf.append(StringValue.LineFeed);
    }
  }
  appendIfNotExists(importedListBuf,oneline,"String_Node_Str" + targetClassMeta.packageName + "String_Node_Str"+ targetClassMeta.name+ "String_Node_Str");
  if (config.junitVersion == JUnitVersion.version3) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str" + config.testCaseClassNameToExtend + "String_Node_Str");
  }
 else   if (config.junitVersion == JUnitVersion.version4) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
  if (config.mockObjectFramework == MockObjectFramework.EasyMock) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.JMock2) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.JMockit) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.Mockito) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
  if (importedListBuf.length() > 0) {
    Matcher matcher=RegExp.PatternObject.PackageDefArea_Group.matcher(src.replaceAll(RegExp.CRLF,StringValue.Space));
    if (matcher.find()) {
      String packageDef=matcher.group(1);
      String CRLF=StringValue.CarriageReturn + StringValue.LineFeed;
      String replacement=packageDef + CRLF + CRLF+ importedListBuf.toString().replaceAll("String_Node_Str",StringValue.Empty);
      dest=dest.replaceFirst(packageDef,replacement);
    }
 else {
      dest=importedListBuf.toString() + dest;
    }
  }
  return dest;
}

Fixed version (ground truth):
String addRequiredImportList(String src,Configulation config){
  String dest=src;
  String oneline=TrimFilterUtil.doAllFilters(src);
  StringBuilder importedListBuf=new StringBuilder();
  for (  String imported : targetClassMeta.importedList) {
    String newOne="String_Node_Str" + imported + "String_Node_Str";
    if (!oneline.matches(RegExp.Anything_ZeroOrMore_Min + newOne + RegExp.Anything_ZeroOrMore_Min)) {
      importedListBuf.append(newOne);
      importedListBuf.append(StringValue.CarriageReturn);
      importedListBuf.append(StringValue.LineFeed);
    }
  }
  appendIfNotExists(importedListBuf,oneline,"String_Node_Str" + targetClassMeta.packageName + "String_Node_Str"+ targetClassMeta.name+ "String_Node_Str");
  if (config.junitVersion == JUnitVersion.version3) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str" + config.testCaseClassNameToExtend + "String_Node_Str");
  }
 else   if (config.junitVersion == JUnitVersion.version4) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
  if (config.mockObjectFramework == MockObjectFramework.EasyMock) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.JMock2) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.JMockit) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
 else   if (config.mockObjectFramework == MockObjectFramework.Mockito) {
    appendIfNotExists(importedListBuf,oneline,"String_Node_Str");
  }
  if (importedListBuf.length() > 0) {
    Matcher matcher=RegExp.PatternObject.PackageDefArea_Group.matcher(src.replaceAll(RegExp.CRLF,StringValue.Space));
    if (matcher.find()) {
      String packageDef=matcher.group(1);
      String CRLF=StringValue.CarriageReturn + StringValue.LineFeed;
      String replacement=packageDef + CRLF + CRLF+ importedListBuf.toString().replaceAll("String_Node_Str",StringValue.Empty);
      dest=dest.replaceFirst(packageDef,replacement);
    }
 else {
      dest=importedListBuf.toString() + dest;
    }
  }
  return dest;
}