[java-client][okhttp-gson] no oauth2 usage when hasOAuthMethods is false

[jmini]

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@wing328 (author of #1838).
Java tech committee @bbdouglas (2017/07) @JFCote (2017/08) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01)

Description of the PR

Follow up from of PR #1838:

The org.apache.oltu.oauth2:org.apache.oltu.oauth2.client is now only included if hasOAuthMethods is true. See:

This means that when a spec do not use OAuth, the generated code should not use any of the classes provided by the dependency. Otherwise maven build for the generated lib looks like this:

[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR : 
[INFO] -------------------------------------------------------------
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[10,37] package org.apache.oltu.oauth2.client does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[11,45] package org.apache.oltu.oauth2.client.request does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[12,45] package org.apache.oltu.oauth2.client.request does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[13,64] package org.apache.oltu.oauth2.client.request.OAuthClientRequest does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[14,46] package org.apache.oltu.oauth2.client.response does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[15,47] package org.apache.oltu.oauth2.common.exception does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[16,47] package org.apache.oltu.oauth2.common.exception does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[17,51] package org.apache.oltu.oauth2.common.message.types does not exist
[ERROR] <java-okhttp-gson project>/src/main/java/...../okhttpgson/auth/RetryingOAuth.java:[25,13] cannot find symbol
  symbol:   class OAuthClient
  location: class xxxxx.okhttpgson.auth.RetryingOAuth
...

This PR add more {#hasOAuthMethods}..{/hasOAuthMethods} to the templates.

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[wing328]

Thanks for the fix!