calling an URL with no path

When trying to execute a query using an http async client if the URL provided has no path, the generated request has no path header. This is not correct: according to standards in such a case the path header should be set to "/". This leads to a 400 http response.

http-outgoing-3 >> "GET ?utm_source=DP_TBMG&utm_medium=M&utm_campaign=Brand_2013Q2&utm_content=PreRoll&t360=000000500000000000361 HTTP/1.1[\r][\n]" (Wire.java:54)
http-outgoing-3 >> "Host: www.lentillesmoinscheres.com[\r][\n]" (Wire.java:54)
http-outgoing-3 >> "Connection: Keep-Alive[\r][\n]" (Wire.java:54)
http-outgoing-3 >> "User-Agent: Apache-HttpAsyncClient/4.0-beta3 (java 1.5)[\r][\n]" (Wire.java:54)
http-outgoing-3 >> "[\r][\n]" (Wire.java:54)
http-outgoing-3 192.168.0.25:44392<->93.184.220.20:80[ACTIVE][r:w]: Event cleared [w] (LoggingIOSession.java:112)
http-outgoing-3 [ACTIVE] Request ready (LoggingAsyncRequestExecutor.java:83)
http-outgoing-3 192.168.0.25:44392<->93.184.220.20:80[ACTIVE][r:r]: 504 bytes read (LoggingIOSession.java:189)
http-outgoing-3 << "HTTP/1.0 400 Bad Request[\r][\n]" (Wire.java:54)
http-outgoing-3 << "Content-Type: text/html[\r][\n]" (Wire.java:54)
http-outgoing-3 << "Content-Length: 349[\r][\n]" (Wire.java:54)
http-outgoing-3 << "Connection: close[\r][\n]" (Wire.java:54)
http-outgoing-3 << "Date: Tue, 21 May 2013 08:44:40 GMT[\r][\n]" (Wire.java:54)
http-outgoing-3 << "Server: ECSF (fra/D4F6)[\r][\n]" (Wire.java:54)
http-outgoing-3 << "[\r][\n]" (Wire.java:54)