Program: 167690
Project: 167690
Buggy source:
public IfHandler(){
  super("String_Node_Str",true);
  condition=new ConditionArgument(this);
  condition.addCantAppearAfter(helpArg);
  of=new ArgumentWithValue(this,new DefaultCompleter(new CandidatesProvider(){
    @Override public Collection<String> getAllCandidates(    CommandContext ctx){
      return Collections.singletonList("String_Node_Str");
    }
  }
),1,"String_Node_Str");
  of.addRequiredPreceding(condition);
  final ArgumentWithValue line=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      final ParsedCommandLine args=ctx.getParsedCommandLine();
      final String lnStr=of.getValue(args);
      if (lnStr == null) {
        return -1;
      }
      final String originalLine=args.getOriginalLine();
      String conditionStr;
      try {
        conditionStr=condition.getValue(args,true);
      }
 catch (      CommandFormatException e) {
        return -1;
      }
      int i=originalLine.indexOf(conditionStr);
      if (i < 0) {
        return -1;
      }
      i=originalLine.indexOf("String_Node_Str",i + conditionStr.length());
      if (i < 0) {
        return -1;
      }
      final String cmd=originalLine.substring(i + 3);
      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);
    }
  }
,Integer.MAX_VALUE,"String_Node_Str"){
  }
;
  line.addRequiredPreceding(of);
}

Fixed version (ground truth):
public IfHandler(){
  super("String_Node_Str",true);
  condition=new ConditionArgument(this);
  condition.addCantAppearAfter(helpArg);
  of=new ArgumentWithValue(this,new DefaultCompleter(new CandidatesProvider(){
    @Override public Collection<String> getAllCandidates(    CommandContext ctx){
      return Collections.singletonList("String_Node_Str");
    }
  }
),1,"String_Node_Str");
  of.addRequiredPreceding(condition);
  final ArgumentWithValue line=new ArgumentWithValue(this,new CommandLineCompleter(){
    @Override public int complete(    CommandContext ctx,    String buffer,    int cursor,    List<String> candidates){
      final ParsedCommandLine args=ctx.getParsedCommandLine();
      final String lnStr=of.getValue(args);
      if (lnStr == null) {
        return -1;
      }
      final String substitutedLine=args.getSubstitutedLine();
      String conditionStr;
      try {
        conditionStr=condition.getValue(args,true);
      }
 catch (      CommandFormatException e) {
        return -1;
      }
      int i=substitutedLine.indexOf(conditionStr);
      if (i < 0) {
        return -1;
      }
      i=substitutedLine.indexOf("String_Node_Str",i + conditionStr.length());
      if (i < 0) {
        return -1;
      }
      final String cmd=substitutedLine.substring(i + 3);
      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);
    }
  }
,Integer.MAX_VALUE,"String_Node_Str"){
  }
;
  line.addRequiredPreceding(of);
}