Add support for java streaming proto

Test: m services with ag/15937571 applied
Bug: 199427116
Change-Id: Icf262efa015900f14d9f4cabe3b8af7ec872a668
diff --git a/java/proto.go b/java/proto.go
index 8731822..983a13c 100644
--- a/java/proto.go
+++ b/java/proto.go
@@ -102,6 +102,9 @@
 	if String(p.Proto.Plugin) == "" {
 		var typeToPlugin string
 		switch String(p.Proto.Type) {
+		case "stream":
+			flags.proto.OutTypeFlag = "--javastream_out"
+			typeToPlugin = "javastream"
 		case "micro":
 			flags.proto.OutTypeFlag = "--javamicro_out"
 			typeToPlugin = "javamicro"