Boilerplate code to generate a general usage Retrofit2 http model client

RetrofitHttpClientProvider.java

import lombok.Getter;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import okhttp3.OkHttpClient;
import retrofit2.Retrofit;
import retrofit2.converter.jackson.JacksonConverterFactory;

import java.net.Authenticator;
import java.net.InetSocketAddress;
import java.net.PasswordAuthentication;
import java.net.Proxy;
import java.util.concurrent.TimeUnit;

import static okhttp3.OkHttpClient.Builder;

@Slf4j
@Getter
@Setter
public final class RetrofitHttpClientProvider {
    
    private boolean useProxy = false;
    private String proxyHost;
    private Integer proxyPort;
    private String proxyUsername;
    private String proxyPassword;
    
    /** Retrofit throws a runtime error if the string url does not end with a slash. **/
    private static String addSlashStringIfLastCharIsNotSlash(String baseUrl) {
        Character lastChar = baseUrl.charAt(baseUrl.length() - 1);
        if (!lastChar.equals('/'))
            baseUrl = baseUrl + '/';
        return baseUrl;
    }
    
    public <T> T provideRetrofitHttpClient(String baseUrl, Class<T> classToInstantiate) {
        baseUrl = addSlashStringIfLastCharIsNotSlash(baseUrl);
        Retrofit retrofit = new Retrofit.Builder()
            .baseUrl(baseUrl)
            .client(provideOkHttpClient())
            .addConverterFactory(JacksonConverterFactory.create())
            .build();
        return retrofit.create(classToInstantiate);
    }
    
    private OkHttpClient provideOkHttpClient() {
        Builder okhttpClientBuilder = new Builder();
        okhttpClientBuilder
            .connectTimeout(30, TimeUnit.SECONDS)
            .readTimeout(30, TimeUnit.SECONDS)
            .writeTimeout(30, TimeUnit.SECONDS);
        if (useProxy)
            okhttpClientBuilder.proxy(provideProxy());
        return okhttpClientBuilder.build();
    }
    
    private Proxy provideProxy() {
        InetSocketAddress proxyAddr = new InetSocketAddress(proxyHost, proxyPort);
        Proxy proxy = new Proxy(Proxy.Type.HTTP, proxyAddr);
        Authenticator.setDefault(proxyProxyAuthenticator());
        return proxy;
    }
    
    private Authenticator proxyProxyAuthenticator() {
        return new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                if (getRequestingHost().equalsIgnoreCase(proxyHost)) {
                    return new PasswordAuthentication(proxyUsername, proxyPassword.toCharArray());
                }
                return null;
            }
        };
    }
    
}