public Builder setMtu(int mtu) {
            mConfig.mtu = mtu;
            return this;
        }
Set the maximum transmission unit (MTU) of the VPN interface. If it is not set, the
default value in the operating system will be used.

@param mtu Maximum transmission unit (MTU).
@return this {@link Builder} object to facilitate chaining method calls.
netbare-core/src/main/java/com/github/megatronking/netbare/NetBareConfig.java