Merge pull request #339 from WendySanarwanto/develop

Added info under `Prepared dependencies` section, to suggest Linux Ubuntu's users, using Oracle JDK 8, instead of OpenJDK 8, to avoid error build

Author: zhaohong

README.md

@@ -74,6 +74,7 @@ git clone https://github.com/tronprotocol/java-tron.git
 ## Prepare dependencies
 
 * JDK 1.8 (JDK 1.9+ are not supported yet)
+* On Linux Ubuntu system (e.g. Ubuntu 16.04.4 LTS), ensure that the machine has [__Oracle JDK 8__](https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-get-on-ubuntu-16-04), instead of having __Open JDK 8__ in the system. If you are building the source code by using __Open JDK 8__, you will get [__Build Failed__](https://github.com/tronprotocol/java-tron/issues/337) result.
 
 ## Building from source code