Motivation:
When SpdyHttpEncoder attempts to create an SpdyHeadersFrame from a HttpResponse an IllegalArgumentException is thrown if the original HttpResponse contains a header that includes uppercase characters. The IllegalArgumentException is thrown due to the additional validation check introduced by #4047.
Previous versions of the SPDY codec would handle this by converting the HTTP header name to lowercase before adding the header to the SpdyHeadersFrame.
Modifications:
Convert the header name to lowercase before adding it to SpdyHeaders
Result:
SpdyHttpEncoder can now convert a valid HttpResponse into a valid SpdyFrame