String with escape sequence

[he11b0rn]

String with one \
"[{\"fieldId\":\"TextField\"}]"
does not work

String with 2
"[{\\"fieldId\\":\\"TextField\\"}]"
works fine

How to make it work with 1 slash?

const input = `"[{\\"fieldId\\":\\"TextField\\"}]"`
const inputStream = CharStream.fromString(input);
const lexer = new FormulaLexer(inputStream);
const tokenStream = new CommonTokenStream(lexer);
const parser = new FormulaParser(tokenStream);
const tree = parser.prog();

const visitor = new FormulaVisitor()
const result = visitor.visit(tree)

STRINGJ
    : '"' (ESC | SAFECODEPOINT)* '"'
    ;

fragment SLASH: '\\';

fragment ESC
    : SLASH (["\\/bfnrt] | UNICODE)
    ;

fragment UNICODE
    : 'u' HEX HEX HEX HEX
    ;

fragment HEX
    : [0-9a-fA-F]
    ;

fragment SAFECODEPOINT
    : ~ ["\\\u0000-\u001F]
    ;

[mike-lischke]

That's more of a general programming question. Please ask that on Stackoverflow.com.