question: private JsonParserException createHelpfulException ( char first , char [ ] expected , int failurePosition ) throws JsonParserException { StringBuilder errorToken = new StringBuilder ( first + ( expected == null ? "" : new String ( expected , 0 , failurePosition ) ) ) ; while ( isAsciiLetter ( peekChar ( ) ) && errorToken . length ( ) < 15 ) errorToken . append ( ( char ) advanceChar ( ) ) ; return createParseException ( null , "Unexpected token '" + errorToken + "'" + ( expected == null ? "" : ". Did you mean '" + first + new String ( expected ) + "'?" ) , true ) ; }
target:  Throws a helpful exception based on the current alphanumeric token.