OZG-6990 extend grpc util: add string constant

ozgcloud-common-lib/src/main/java/de/ozgcloud/common/grpc/GrpcUtil.java

@@ -41,7 +41,8 @@ public class GrpcUtil {
 	public static final Key<byte[]> HEADER_KEY_USER_ID = createKeyOf("USER_ID-bin");
 	public static final Key<byte[]> HEADER_KEY_USER_NAME = createKeyOf("USER_NAME-bin");
 	public static final Key<byte[]> HEADER_KEY_CLIENT_NAME = createKeyOf("CLIENT_NAME-bin");
-	public static final Key<byte[]> HEADER_KEY_REQUEST_ID = createKeyOf("REQUEST_ID-bin");
+	public static final String KEY_REQUEST_ID = "REQUEST_ID-bin";
+	public static final Key<byte[]> HEADER_KEY_REQUEST_ID = createKeyOf(KEY_REQUEST_ID);
 	public static final Key<byte[]> HEADER_KEY_ACCESS_LIMITED_ORGAID = createKeyOf("ACCESS_LIMITED_TO_ORGANISATORISCHEEINHEITENID-bin");
 	public static final Key<byte[]> HEADER_KEY_ACCESS_LIMITED = createKeyOf("ACCESS_LIMITED-bin");