findSubstitutions () {
        return Property.findSubstitutions(this.toJSON());
    }
Returns all the substitutions (variables) that are needed (or referenced) in this property (recursively).

@returns {String[]}

@example
// returns ['host', 'path1']
prop.findSubstitutions({request: 'https://{{host}}/{{path1}}-action/'});

@see {Property.findSubstitutions}