How I can do unlink() for account at Android (with API v2)?

Hello,

I use this DropboxClientFactory:

public class DropboxClientFactory {

    private static DbxClientV2 sDbxClient;

    public static void init(String accessToken) {
    	if (sDbxClient == null) {
            DbxRequestConfig requestConfig = DbxRequestConfig.newBuilder("myApp").build();
            sDbxClient = new DbxClientV2(requestConfig, accessToken);
    	}
    }
    
    public static DbxClientV2 getClient() {
        if (sDbxClient == null) {
            throw new IllegalStateException("Client not initialized.");
        }
        return sDbxClient;
    }

    public static Boolean tokenRevoke() {
    	Boolean result = false;
    	if (sDbxClient != null) {
    		try {
    		   sDbxClient.auth().tokenRevoke();
    		   result = true;
    		} catch (DbxApiException e) {
    		} catch (DbxException e) {
	       	}
    	} 
		return result;
    }   
}

I have some questions/problems:

1. In most examples, DbxRequestConfig is like this (with .withHttpRequestor(new OkHttp3Requestor(OkHttp3Requestor.defaultOkHttpClient())))

DbxRequestConfig requestConfig = DbxRequestConfig.newBuilder("examples-v2-demo")
.withHttpRequestor(new OkHttp3Requestor(OkHttp3Requestor.defaultOkHttpClient()))
.build();

I use it without "OkHttpRequestor". Is it necessary?

I would like to add it, but i recive the error on it: "The type okhttp3.OkHttpClient cannot be resolved. It is indirectly referenced from required .class files". How could I resolve it?

2. App links to dropbox and upload/download the file without the problem. But on revoke the token (calling tokenRevoke() ) i recieve the error: "android.os.NetworkOnMainThreadException".  And this error is not catched by DbxApiException and  DbxException.

What is wrong? Why this error is not catched? What type of Exception i need to use to catch all errors of Dropbox?

I use general "Exception e", it catches the error, but "e.getMessage()" returns NULL.

Thanks in advance.