Show the optional field on document and function comment

[chrisdukakis]

Redirecting the original issue opened in JS repo: iotaledger/iota.js#261
@thieuanh1995hn wrote:
"Hi guys i think you should show us that what field can define null (optional) on Java Client API which you have done well in Java script library : https://iotaledger.github.io/iota.lib.java/javadoc/jota/IotaAPI.html#sendTransfer-java.lang.String-int-int-int-java.util.List-java.util.List-java.lang.String-boolean-boolean-
For example. In sendTransfer Api . We can define inputs parameter = null because it is optional and the code show that truth."

[thieuanh1995hn]

Thank you @chrisdukakis