Program: 21630
Project: 21630
Buggy source:
public static String getRelativeURL(URL context,URL url){
  String urlStr=url.toExternalForm();
  if (context.getProtocol() == null || !context.getProtocol().equals(url.getProtocol())) {
    return urlStr;
  }
  if (context.getAuthority() == null || !context.getAuthority().equals(url.getAuthority())) {
    return urlStr;
  }
  String contextPath=context.getPath();
  String urlPath=url.getPath();
  String strippedContextPath=contextPath;
  String strippedUrlPath=urlPath;
  if (contextPath.startsWith("String_Node_Str")) {
    strippedContextPath=contextPath.substring(1);
    if (urlPath.startsWith("String_Node_Str")) {
      strippedUrlPath=urlPath.substring(1);
    }
 else {
      throw new IllegalStateException("String_Node_Str" + "String_Node_Str" + context + "String_Node_Str"+ url);
    }
  }
  String codebasePath=strippedContextPath;
  if (!strippedContextPath.endsWith("String_Node_Str")) {
    int slashIndex=strippedContextPath.lastIndexOf('/');
    if (slashIndex < 0) {
      codebasePath="String_Node_Str";
    }
 else     if (slashIndex == 0) {
      throw new IllegalStateException("String_Node_Str" + context);
    }
 else {
      codebasePath=strippedContextPath.substring(0,slashIndex);
    }
  }
  String[] codebasePathSegments=codebasePath.split("String_Node_Str");
  String[] urlPathSegment=strippedUrlPath.split("String_Node_Str");
  int i=0;
  for (; i < codebasePathSegments.length; i++) {
    if (i >= urlPathSegment.length) {
      break;
    }
    if (!codebasePathSegments[i].equals(urlPathSegment[i])) {
      break;
    }
  }
  int matchingSegments=i;
  if (matchingSegments == 0) {
    String relativeUrl=url.getFile();
    if (url.getRef() != null) {
      relativeUrl+="String_Node_Str" + url.getRef();
    }
    if (codebasePathSegments.length == 0 && relativeUrl.startsWith("String_Node_Str")) {
      relativeUrl=relativeUrl.substring(1);
    }
    return relativeUrl;
  }
  int codebaseNonMatchingSegments=codebasePathSegments.length - (matchingSegments);
  String parentString="String_Node_Str";
  for (int j=0; j < codebaseNonMatchingSegments; j++) {
    parentString+="String_Node_Str";
  }
  String relativeUrl=parentString;
  int urlNonMatchingSegments=urlPathSegment.length - (matchingSegments);
  for (int j=0; j < urlNonMatchingSegments; j++) {
    relativeUrl+=urlPathSegment[matchingSegments + j] + "String_Node_Str";
  }
  if (urlPath.endsWith("String_Node_Str") && !relativeUrl.endsWith("String_Node_Str")) {
    relativeUrl+="String_Node_Str";
  }
 else   if (!urlPath.endsWith("String_Node_Str") && relativeUrl.endsWith("String_Node_Str")) {
    relativeUrl=relativeUrl.substring(0,relativeUrl.length() - 1);
  }
  if (url.getQuery() != null) {
    relativeUrl+="String_Node_Str" + url.getQuery();
  }
  if (url.getRef() != null) {
    relativeUrl+="String_Node_Str" + url.getRef();
  }
  return relativeUrl;
}

Fixed version (ground truth):
public static String getRelativeURL(URL context,URL url){
  String urlStr=url.toExternalForm();
  if (context.getProtocol() == null || !context.getProtocol().equals(url.getProtocol())) {
    return urlStr;
  }
  if (context.getAuthority() != null && !context.getAuthority().equals("String_Node_Str") && !context.getAuthority().equals(url.getAuthority())) {
    return urlStr;
  }
  String contextPath=context.getPath();
  String urlPath=url.getPath();
  String strippedContextPath=contextPath;
  String strippedUrlPath=urlPath;
  if (contextPath.startsWith("String_Node_Str")) {
    strippedContextPath=contextPath.substring(1);
    if (urlPath.startsWith("String_Node_Str")) {
      strippedUrlPath=urlPath.substring(1);
    }
 else {
      throw new IllegalStateException("String_Node_Str" + "String_Node_Str" + context + "String_Node_Str"+ url);
    }
  }
  String codebasePath=strippedContextPath;
  if (!strippedContextPath.endsWith("String_Node_Str")) {
    int slashIndex=strippedContextPath.lastIndexOf('/');
    if (slashIndex < 0) {
      codebasePath="String_Node_Str";
    }
 else     if (slashIndex == 0) {
      throw new IllegalStateException("String_Node_Str" + context);
    }
 else {
      codebasePath=strippedContextPath.substring(0,slashIndex);
    }
  }
  String[] codebasePathSegments=codebasePath.split("String_Node_Str");
  String[] urlPathSegment=strippedUrlPath.split("String_Node_Str");
  int i=0;
  for (; i < codebasePathSegments.length; i++) {
    if (i >= urlPathSegment.length) {
      break;
    }
    if (!codebasePathSegments[i].equals(urlPathSegment[i])) {
      break;
    }
  }
  int matchingSegments=i;
  if (matchingSegments == 0) {
    String relativeUrl=url.getFile();
    if (url.getRef() != null) {
      relativeUrl+="String_Node_Str" + url.getRef();
    }
    if (codebasePathSegments.length == 0 && relativeUrl.startsWith("String_Node_Str")) {
      relativeUrl=relativeUrl.substring(1);
    }
    return relativeUrl;
  }
  int codebaseNonMatchingSegments=codebasePathSegments.length - (matchingSegments);
  String parentString="String_Node_Str";
  for (int j=0; j < codebaseNonMatchingSegments; j++) {
    parentString+="String_Node_Str";
  }
  String relativeUrl=parentString;
  int urlNonMatchingSegments=urlPathSegment.length - (matchingSegments);
  for (int j=0; j < urlNonMatchingSegments; j++) {
    relativeUrl+=urlPathSegment[matchingSegments + j] + "String_Node_Str";
  }
  if (urlPath.endsWith("String_Node_Str") && !relativeUrl.endsWith("String_Node_Str")) {
    relativeUrl+="String_Node_Str";
  }
 else   if (!urlPath.endsWith("String_Node_Str") && relativeUrl.endsWith("String_Node_Str")) {
    relativeUrl=relativeUrl.substring(0,relativeUrl.length() - 1);
  }
  if (url.getQuery() != null) {
    relativeUrl+="String_Node_Str" + url.getQuery();
  }
  if (url.getRef() != null) {
    relativeUrl+="String_Node_Str" + url.getRef();
  }
  return relativeUrl;
}