fix(http2): don't add client content-length if method doesn't require it

src/headers.rs

@@ -1,6 +1,7 @@
 use bytes::BytesMut;
 use http::header::{HeaderValue, OccupiedEntry, ValueIter};
 use http::header::{CONTENT_LENGTH, TRANSFER_ENCODING};
+use http::method::Method;
 use http::HeaderMap;
 
 pub fn connection_keep_alive(value: &HeaderValue) -> bool {
@@ -57,6 +58,13 @@ pub fn content_length_parse_all_values(values: ValueIter<'_, HeaderValue>) -> Op
     }
 }
 
+pub fn method_has_defined_payload_semantics(method: &Method) -> bool {
+    match *method {
+        Method::GET | Method::HEAD | Method::DELETE | Method::CONNECT => false,
+        _ => true,
+    }
+}
+
 pub fn set_content_length_if_missing(headers: &mut HeaderMap, len: u64) {
     headers
         .entry(CONTENT_LENGTH)