Avoid escaping when no property is involved

Due to FELIX-2366 escape character ('\') is removed in order to be able to escape properties. However when what's escaped is something not related to a property, like a literal '\\\\s{0,2}' the escape character gets also removed.

For example, in the previous case:

a=\\\\s{0,2}

The same value should be expected for a, but 's{0,2}' is obtained.