Merge pull request #257 from jc0803kevin/master

[Project submission] Filecoin Java SDK

Author: longfeiWan9

projects/developer_tooling/Filecoin-java-sdk-en.md

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+## Project Name
+Filecoin Java SDK
+
+## Category 
+Developer Tooling
+
+## Project Description
+Supporting features:
+
++ all Lotus RPC API
++ offline wallet creation(BLS, secp256k1 & multisig), 
++ Transfer Signature, offline multi-signature, etc.
+
+## Project Status
+Developing
+
+## Previews
+
+* Data used for signature
+
+![Data used for signature](./images/Sign%20Data.jpg)
+
+* Build multi-signature address parameters
+
+![Build multi-signature address parameters](./images/Build%20multi-signature%20address%20parameters.jpg)
+
+* Blake2b Digital signature refer to [Blake2b](https://github.com/alphazero/Blake2b)
+* Cbor Encoding format refer to [Cbor](https://github.com/whyrusleeping/cbor-gen)
+
+## Target Audience
+Developers of exchanges, wallets or even applications.
+
+## Rough estimated user base (if applicable)
+
+N/A
+
+## Github repo
+
+https://github.com/jc0803kevin/FilecoinJ
+
+## Website
+
+N/A
+
+
+## Docs
+https://github.com/jc0803kevin/FilecoinJ
+
+## Team Info
+A small team.
+
+### Team Size 
+
+1 
+
+### Team members  
+Jc0803kevin
+
+## How the community can engage
+
+GitHub Discussion: https://github.com/filecoin-project/community/discussions/252   
+Email: [email protected]  
+
+
+## How to Contribute
+
+N/A