fl=my-hyphen-field in query params parsed as "my" instead of "my-hyphen-field".
OAS.search.ReturnFields use method getId() from OAS.search.QueryParsing
in which check chars "if (!Character.isJavaIdentifierPart(ch) && ch != '.')"
Hyphen is not JavaIdentifierPart and this check break when first "-" is found.
This problem solve by passing '-' to check:
if (!Character.isJavaIdentifierPart(ch) && ch != '.' && ch != '-') break;
But I don't know how it can affect on whole project.