public ClientFactoryBuilder http2InitialConnectionWindowSize(int http2InitialConnectionWindowSize) {
        checkArgument(http2InitialConnectionWindowSize >= DEFAULT_WINDOW_SIZE,
                      "http2InitialConnectionWindowSize: %s (expected: >= %s and <= %s)",
                      http2InitialConnectionWindowSize, DEFAULT_WINDOW_SIZE, MAX_INITIAL_WINDOW_SIZE);
        option(ClientFactoryOptions.HTTP2_INITIAL_CONNECTION_WINDOW_SIZE, http2InitialConnectionWindowSize);
        return this;
    }
Sets the
<a href="https://datatracker.ietf.org/doc/html/rfc7540#section-6.9.2">initial connection flow-control
window size</a>. The HTTP/2 connection is first established with
{@value Http2CodecUtil#DEFAULT_WINDOW_SIZE} bytes of connection flow-control window size,
and it is changed if and only if {@code http2InitialConnectionWindowSize} is set.
Note that this setting affects the connection-level window size, not the window size of streams.

@see #http2InitialStreamWindowSize(int)
core/src/main/java/com/linecorp/armeria/client/ClientFactoryBuilder.java