Added the Kleros Curate Service to obtain address tags

[jaybuidl]

Resolves #2607 for Android only.

Overview

The implementation provides a new KlerosCurateService with a request function returning an AddressInformation entity.

The current service provides tags for addresses on Ethereum mainnet only (chainid 1). It should not be queried for non-Ethereum mainnet addresses at this stage.

Under the hood, the dataset of Ethereum mainnet tags is spread out across 2 registries deployed on Ethereum mainnet and Gnosis chain. If the address is not found the first registry, then it is looked up in the second one.

Looking up an address in a registry consists in making a call to the subgraph API, parsing the IPFS content identifier and retrieving the corresponding JSON file from IPFS.

If the address is not present in the registry, the service returns a static NULL_ADDRESS_INFORMATION object (null object pattern).

Testing

The service can be tested as follow:

@Test
public void klerosCurateService() {
    // Not a mock: this is testing against a live service.
    OkHttpClient httpClient = new OkHttpClient.Builder()
            .connectTimeout(7, TimeUnit.SECONDS)
            .readTimeout(7, TimeUnit.SECONDS)
            .writeTimeout(7, TimeUnit.SECONDS)
            .retryOnConnectionFailure(false)
            .build();

    KlerosCurateService curate = new KlerosCurateService(httpClient);

    try {
        AddressInformation info = curate.request("0xdAC17F958D2ee523a2206206994597C13D831ec7");
        assertEquals("Tether: USDT Stablecoin", info.publicNameTag);
        assertEquals("0xdAC17F958D2ee523a2206206994597C13D831ec7", info.contractAddress);
        assertEquals("https://tether.to/", info.uiWebsiteLink);
        assertEquals("The contract of Tether (USDT) stablecoin.", info.publicNote);

        info = curate.request("0xe592427a0aece92de3edee1f18e0157c05861564");
        assertEquals("Uniswap V3: Router 1", info.publicNameTag);
        assertEquals("0xe592427a0aece92de3edee1f18e0157c05861564", info.contractAddress);
        assertEquals("https://app.uniswap.org/#/swap", info.uiWebsiteLink);
        assertEquals("Version 1 of the Uniswap V3 Router.", info.publicNote);

        info = curate.request("0xC18360217D8F7Ab5e7c516566761Ea12Ce7F9D72");
        assertEquals(KlerosCurateService.NULL_ADDRESS_INFORMATION, info);
    } catch (IOException e) {
        fail();
    }
}

@gmkung @alcercu @AndreiMVP

[JamesSmartCell]

@jaybuidl this is awesome; it's complementary to our TokenScript approach in some respects. I can certainly wire it into mainnet requests.

[gmkung]

@hboon @JamesSmartCell , wondering how you guys are progressing with the UI parts of this PR?