core/play/src/main/java/play/mvc/Results.java
public static Result preconditionRequired(File content, FileMimeTypes fileMimeTypes) {
    return status(PRECONDITION_REQUIRED, content, fileMimeTypes);
  }
public static Result preconditionRequired(File content, FileMimeTypes fileMimeTypes) {
    return status(PRECONDITION_REQUIRED, content, fileMimeTypes);
  }
Generates a 428 Precondition Required result.

@param content The file to send.
@param fileMimeTypes Used for file type mapping.
@return the result