core/src/main/java/com/orientechnologies/orient/core/sql/parser/OCreateIndexStatement.java
private String[] calculateProperties(OCommandContext ctx) {
    if (propertyList == null) {
      return null;
    }
    return propertyList.stream().map(x -> x.getCompleteKey()).collect(Collectors.toList()).toArray(new String[] {});
  }
private String[] calculateProperties(OCommandContext ctx) {
    if (propertyList == null) {
      return null;
    }
    return propertyList.stream().map(x -> x.getCompleteKey()).collect(Collectors.toList()).toArray(new String[] {});
  }
*
returns the list of property names to be indexed

@param ctx
@return