Ignore spaces, but allow text with spaces - antlr

Question

I need to write a simple antlr4 grammar for expressions like this:
{paramName=simple text} //correct
{ paramName = simple text} //correct
{bad param=text} //incorrect
First two expression is almost equal. The difference is a space before and after parameter name. Third is incorrect, spaces not allowed in parameter name. I write a grammar:
grammar Test;
prog : '{' paramName '=' paramValue '}' ;
paramName : PARAM_NAME ;
paramValue : TEXT_WITH_SPACES ;
PARAM_NAME : [A-Za-zА-Яа-я_] [A-Za-zА-Яа-я_0-9]* ;
TEXT_WITH_SPACES : (LETTERS_EN|' ')+ ;
WS : [ ]+ -> skip;
fragment LETTERS_EN : ([A-Za-z]) ;
So, the task is ignore spaces around parameter name, but allow spaces in parameter value. But when I add a space inside rule TEXT_WITH_SPACES, my second expression highlight as icorrect.
screenshot
What can I do? Thank you in advance!

Answer 1

Ignore all spaces, but consider them to be "end of word", and allow more words in the value:
grammar Test;
prog : '{' paramName '=' paramValue '}' ;
paramName : WORD ;
paramValue : WORD+ ;
WORD : [A-Za-zА-Яа-я_] [A-Za-zА-Яа-я_0-9]* ;
WS : [ ]+ -> skip;
Update: To preserve spaces in the value:
grammar Test;
prog : '{' paramName '=' paramValue '}' ;
paramName : WORD ;
paramValue : WORD | MULTIWORD ;
MULTIWORD : WORD ((' ')+ WORD)* ;
WORD : [A-Za-zА-Яа-я_] [A-Za-zА-Яа-я_0-9]* ;
WS : [ ]+ -> skip;
This is based on MULTIWORD matching multiple words with nothing but space in between them, and other cases being matched by sequence of WORD and WS.