Program: 56462
Project: 56462
Buggy source:
public boolean validate(CellType cellType,Object value){
  ValidationType vtype=_validation.getValidationType();
  if (vtype == ValidationType.ANY) {
    return true;
  }
  if (vtype != ValidationType.TEXT_LENGTH && (value == null || (value instanceof String && ((String)value).length() == 0))) {
    if (_validation.isEmptyCellAllowed()) {
      return true;
    }
  }
  if (cellType == CellType.FORMULA) {
    FormulaEngine engine=EngineFactory.getInstance().createFormulaEngine();
    FormulaExpression expr=engine.parse((String)value,new FormulaParseContext(_sheet,null));
    if (expr.hasError()) {
      return false;
    }
    FormulaResultCellValue result=new FormulaResultCellValue(engine.evaluate(expr,new FormulaEvaluationContext(_sheet)));
    value=result.getValue();
    cellType=result.getCellType();
  }
  CalendarUtil cal=EngineFactory.getInstance().getCalendarUtil();
  boolean success=true;
switch (vtype) {
case INTEGER:
    if (!isInteger(value) || !validateOperation((Number)value)) {
      success=false;
    }
  break;
case DECIMAL:
if (!isDecimal(value) || !validateOperation((Number)value)) {
  success=false;
}
break;
case DATE:
case TIME:
success=(value instanceof Date) && validateOperation(cal.dateToDoubleValue((Date)value));
break;
case LIST:
if (!validateListOperation((value instanceof Date) ? cal.dateToDoubleValue((Date)value) : value)) {
;
success=false;
}
break;
case TEXT_LENGTH:
if (!isString(value) || !validateOperation(Integer.valueOf(value == null ? 0 : ((String)value).length()))) {
success=false;
}
break;
case FORMULA:
success=false;
}
return success;
}

Fixed version (ground truth):
public boolean validate(CellType cellType,Object value){
  ValidationType vtype=_validation.getValidationType();
  if (vtype == ValidationType.ANY) {
    return true;
  }
  if (vtype != ValidationType.TEXT_LENGTH && (value == null || (value instanceof String && ((String)value).length() == 0))) {
    if (_validation.isEmptyCellAllowed()) {
      return true;
    }
  }
  if (cellType == CellType.FORMULA) {
    FormulaEngine engine=EngineFactory.getInstance().createFormulaEngine();
    FormulaExpression expr=engine.parse((String)value,new FormulaParseContext(_sheet,null));
    if (expr.hasError()) {
      return false;
    }
    FormulaResultCellValue result=new FormulaResultCellValue(engine.evaluate(expr,new FormulaEvaluationContext(_sheet)));
    value=result.getValue();
    cellType=result.getCellType();
  }
  CalendarUtil cal=EngineFactory.getInstance().getCalendarUtil();
  boolean success=true;
switch (vtype) {
case INTEGER:
    if (!isInteger(value) || !validateOperation((Number)value)) {
      success=false;
    }
  break;
case DECIMAL:
if (!isDecimal(value) || !validateOperation((Number)value)) {
  success=false;
}
break;
case DATE:
case TIME:
success=(value instanceof Date) && validateOperation(cal.dateToDoubleValue((Date)value));
break;
case LIST:
if (!validateListOperation((value instanceof Date) ? cal.dateToDoubleValue((Date)value) : value)) {
;
success=false;
}
break;
case TEXT_LENGTH:
if ((value != null && !isString(value)) || !validateOperation(Integer.valueOf(value == null ? 0 : ((String)value).length()))) {
success=false;
}
break;
case FORMULA:
success=false;
}
return success;
}