@SuppressWarnings("unchecked")
    public <T> T getOrDefault(final String key, final T defaultValue) {
        return (T) this.ctx.getOrDefault(key, defaultValue);
    }
RPC invoke context.

@author jiachun.fjc
jraft-core/src/main/java/com/alipay/sofa/jraft/rpc/InvokeContext.java