Program: 167684
Project: 167684
Buggy source:
public AttachmentHandler(CommandContext ctx){
  super(ctx,"String_Node_Str",true);
  action=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      if (buffer == null || buffer.isEmpty()) {
        candidates.add(DISPLAY);
        candidates.add(SAVE);
        return cursor;
      }
      if (buffer.equals(DISPLAY) || buffer.equals(SAVE)) {
        candidates.add("String_Node_Str");
        return cursor;
      }
      if (DISPLAY.startsWith(buffer)) {
        candidates.add(DISPLAY + "String_Node_Str");
        return 0;
      }
      if (SAVE.startsWith(buffer)) {
        candidates.add(SAVE + "String_Node_Str");
        return 0;
      }
      return -1;
    }
  }
,0,"String_Node_Str");
  operation=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      final String originalLine=ctx.getParsedCommandLine().getOriginalLine();
      boolean skipWS;
      int wordCount;
      if (Character.isWhitespace(originalLine.charAt(0))) {
        skipWS=true;
        wordCount=0;
      }
 else {
        skipWS=false;
        wordCount=1;
      }
      int cmdStart=1;
      while (cmdStart < originalLine.length()) {
        if (skipWS) {
          if (!Character.isWhitespace(originalLine.charAt(cmdStart))) {
            skipWS=false;
            ++wordCount;
            if (wordCount == 3) {
              break;
            }
          }
        }
 else         if (Character.isWhitespace(originalLine.charAt(cmdStart))) {
          skipWS=true;
        }
        ++cmdStart;
      }
      String cmd;
      if (wordCount == 1) {
        cmd="String_Node_Str";
      }
 else       if (wordCount != 3) {
        return -1;
      }
 else {
        cmd=originalLine.substring(cmdStart);
        int i=cmd.indexOf("String_Node_Str");
        if (i > 0) {
          if (i == cmd.length() - 1) {
            cmd="String_Node_Str";
          }
 else {
            cmd=cmd.substring(i + 1);
          }
        }
      }
      int cmdResult=ctx.getDefaultCommandCompleter().complete(ctx,cmd,cmd.length(),candidates);
      if (cmdResult < 0) {
        return cmdResult;
      }
      int escapeCorrection=0;
      int start=originalLine.length() - 1 - buffer.length();
      while (start - escapeCorrection >= 0) {
        final char ch=originalLine.charAt(start - escapeCorrection);
        if (Character.isWhitespace(ch) || ch == '=') {
          break;
        }
        ++escapeCorrection;
      }
      return buffer.length() + escapeCorrection - (cmd.length() - cmdResult);
    }
  }
,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      String act=getAction(ctx);
      if (!(SAVE.equals(act) || DISPLAY.equals(act))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  operation.addRequiredPreceding(action);
  final FilenameTabCompleter pathCompleter=FilenameTabCompleter.newCompleter(ctx);
  targetFile=new FileSystemPathArgument(this,pathCompleter,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      if (!(SAVE.equals(getAction(ctx)))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  targetFile.addRequiredPreceding(operation);
  overwrite=new ArgumentWithoutValue(this,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      if (!(SAVE.equals(getAction(ctx)))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  headers.addRequiredPreceding(operation);
}

Fixed version (ground truth):
public AttachmentHandler(CommandContext ctx){
  super(ctx,"String_Node_Str",true);
  action=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      if (buffer == null || buffer.isEmpty()) {
        candidates.add(DISPLAY);
        candidates.add(SAVE);
        return cursor;
      }
      if (buffer.equals(DISPLAY) || buffer.equals(SAVE)) {
        candidates.add("String_Node_Str");
        return cursor;
      }
      if (DISPLAY.startsWith(buffer)) {
        candidates.add(DISPLAY + "String_Node_Str");
        return 0;
      }
      if (SAVE.startsWith(buffer)) {
        candidates.add(SAVE + "String_Node_Str");
        return 0;
      }
      return -1;
    }
  }
,0,"String_Node_Str");
  operation=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      final String substitutedLine=ctx.getParsedCommandLine().getSubstitutedLine();
      boolean skipWS;
      int wordCount;
      if (Character.isWhitespace(substitutedLine.charAt(0))) {
        skipWS=true;
        wordCount=0;
      }
 else {
        skipWS=false;
        wordCount=1;
      }
      int cmdStart=1;
      while (cmdStart < substitutedLine.length()) {
        if (skipWS) {
          if (!Character.isWhitespace(substitutedLine.charAt(cmdStart))) {
            skipWS=false;
            ++wordCount;
            if (wordCount == 3) {
              break;
            }
          }
        }
 else         if (Character.isWhitespace(substitutedLine.charAt(cmdStart))) {
          skipWS=true;
        }
        ++cmdStart;
      }
      String cmd;
      if (wordCount == 1) {
        cmd="String_Node_Str";
      }
 else       if (wordCount != 3) {
        return -1;
      }
 else {
        cmd=substitutedLine.substring(cmdStart);
        int i=cmd.indexOf("String_Node_Str");
        if (i > 0) {
          if (i == cmd.length() - 1) {
            cmd="String_Node_Str";
          }
 else {
            cmd=cmd.substring(i + 1);
          }
        }
      }
      int cmdResult=ctx.getDefaultCommandCompleter().complete(ctx,cmd,cmd.length(),candidates);
      if (cmdResult < 0) {
        return cmdResult;
      }
      int escapeCorrection=0;
      int start=substitutedLine.length() - 1 - buffer.length();
      while (start - escapeCorrection >= 0) {
        final char ch=substitutedLine.charAt(start - escapeCorrection);
        if (Character.isWhitespace(ch) || ch == '=') {
          break;
        }
        ++escapeCorrection;
      }
      return buffer.length() + escapeCorrection - (cmd.length() - cmdResult);
    }
  }
,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      String act=getAction(ctx);
      if (!(SAVE.equals(act) || DISPLAY.equals(act))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  operation.addRequiredPreceding(action);
  final FilenameTabCompleter pathCompleter=FilenameTabCompleter.newCompleter(ctx);
  targetFile=new FileSystemPathArgument(this,pathCompleter,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      if (!(SAVE.equals(getAction(ctx)))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  targetFile.addRequiredPreceding(operation);
  overwrite=new ArgumentWithoutValue(this,"String_Node_Str"){
    @Override public boolean canAppearNext(    CommandContext ctx) throws CommandFormatException {
      if (!(SAVE.equals(getAction(ctx)))) {
        return false;
      }
      return super.canAppearNext(ctx);
    }
  }
;
  headers.addRequiredPreceding(operation);
}