code: function identifyRefsInSchemaFields(structure, prefix) {
  
          _.each(structure.schema, (fieldStructure, fieldName) => {
  
              const name = prefix ? prefix + '.' + fieldName : fieldName;
  
              //If field has a schema, then it is a collection
              if (fieldStructure.schema) {
  
                  // is this an object or an array?
                  if (fieldStructure.meta && fieldStructure.meta.type === 'Array') {
                      //array
                      identifyRefsInSchemaFields(fieldStructure, name + '.*')
                  } else {
                      //object. loop through schema.fields
                      identifyRefsInSchemaFields(fieldStructure, name)
                  }
  
              } else if (fieldStructure.meta && fieldStructure.meta.ref) {
                  //ref field found!
                  refFields[name] = 1;
              }
          });
  
  
      }
docs: Identify all refs in the structure and store path names of ref fields
  @param criteria