private static IllegalArgumentException newInvalidSchemeException(URI uri) {
        return new IllegalArgumentException("uri.scheme is not valid: " + uri);
    }
Creates a new builder with the specified {@link RpcRequest} and {@link URI}.

@param server whether this builder will build a server-side context.
@param rpcReq the {@link RpcRequest}.
@param uri the {@link URI} of the request endpoint.
core/src/main/java/com/linecorp/armeria/common/AbstractRequestContextBuilder.java