shapefile for fnml is wrong

[bjdmeest]

In shapes/expression_map.ttl there's an 'alternativepath' directive for rml:returnMap rml:functionExecution:

        sh:path [sh:alternativePath (rml:template 
                                     rml:constant
                                     rml:reference
                                     rml:returnMap
                                     rml:functionExecution)] ;

however, the shape should be

        sh:path [sh:alternativePath (rml:template 
                                     rml:constant
                                     rml:reference
                                     rml:functionExecution)] ;

With an additional directive that IF rml:functionExecution is added, rml:returnMap optionally can also be added. I don't know whether SHACL supports this, otherwise I suggest to put rml:returnMap just as an optional sh:path