core: fix missing comment for headers param
core: fix missing comment for headers param


elandau/grpc-java,elandau/grpc-java,dapengzhang0/grpc-java,ejona86/grpc-java,dapengzhang0/grpc-java,stanley-cheung/grpc-java,dapengzhang0/grpc-java,carl-mastrangelo/grpc-java,carl-mastrangelo/grpc-java,dapengzhang0/grpc-java,grpc/grpc-java,carl-mastrangelo/grpc-java,stanley-cheung/grpc-java,grpc/grpc-java,zhangkun83/grpc-java,stanley-cheung/grpc-java,stanley-cheung/grpc-java,zhangkun83/grpc-java,ejona86/grpc-java,elandau/grpc-java,elandau/grpc-java,ejona86/grpc-java,zhangkun83/grpc-java,ejona86/grpc-java,grpc/grpc-java,grpc/grpc-java,zhangkun83/grpc-java,carl-mastrangelo/grpc-java