what is the use of hostnameverifier in httpsproperties

import java.security.SecureRandom;
import java.security.cert.CertificateException;
import java.security.cert.X509Certificate;

import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSession;
import javax.net.ssl.TrustManager;
import javax.net.ssl.X509TrustManager;

import com.sun.jersey.api.client.Client;
import com.sun.jersey.api.client.config.ClientConfig;
import com.sun.jersey.api.client.config.DefaultClientConfig;
import com.sun.jersey.client.urlconnection.HTTPSProperties;
public class ClientHelper
{
    public static ClientConfig configureClient()
    {
        System.setProperty("jsse.enableSNIExtension", "false");
        TrustManager[] certs = new TrustManager[]
        {
            new X509TrustManager()
            {
                @Override
                public X509Certificate[] getAcceptedIssuers()
                {
                    return null;
                }

                @Override
                public void checkServerTrusted(X509Certificate[] chain, String authType)
                        throws CertificateException
                {
                }

                @Override
                public void checkClientTrusted(X509Certificate[] chain, String authType)
                        throws CertificateException
                {
                }
            }
        };
        SSLContext ctx = null;
        try
        {
            ctx = SSLContext.getInstance("SSL");
            ctx.init(null, certs, new SecureRandom());
        }
        catch (java.security.GeneralSecurityException ex)
        {
        }
        HttpsURLConnection.setDefaultSSLSocketFactory(ctx.getSocketFactory());
        ClientConfig config = new DefaultClientConfig();
        try
        {
            config.getProperties().put(HTTPSProperties.PROPERTY_HTTPS_PROPERTIES, new HTTPSProperties(
                    new HostnameVerifier()
            {
                @Override
                public boolean verify(String hostname, SSLSession session)
                {
                    return true;
                }
            },
                    ctx));
        }
        catch (Exception e)
        {
        }
        return config;
    }

    public static Client createClient()
    {
        return Client.create(ClientHelper.configureClient());
    }

package com.example.client;




import org.glassfish.jersey.client.authentication.HttpAuthenticationFeature;
import org.springframework.http.HttpStatus;
import javax.net.ssl.HostnameVerifier;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.client.Client;
import javax.ws.rs.client.ClientBuilder;
import javax.ws.rs.client.Entity;
import javax.ws.rs.core.Response;

public class JerseyClientGet {
    public static void main(String[] args) {
        String username = "username";
            String password = "p@ssword";
        String input = "{\"userId\":\"12345\",\"name \":\"Viquar\",\"surname\":\"Khan\",\"Email\":\"[email protected]\"}";
        try {
        //SSLContext sc = SSLContext.getInstance("SSL");//Java 6
        SSLContext sc = SSLContext.getInstance("TLSv1");//Java 8
        System.setProperty("https.protocols", "TLSv1");//Java 8


        TrustManager[] trustAllCerts = { new InsecureTrustManager() };
        sc.init(null, trustAllCerts, new java.security.SecureRandom());
        HostnameVerifier allHostsValid = new InsecureHostnameVerifier();

        Client client = ClientBuilder.newBuilder().sslContext(sc).hostnameVerifier(allHostsValid).build();

        HttpAuthenticationFeature feature = HttpAuthenticationFeature.universalBuilder()
                    .credentialsForBasic(username, password).credentials(username, password).build();


            client.register(feature);
                    //PUT request, if need uncomment it 
                    //final Response response = client
                    //.target("https://localhost:7002/VaquarKhanWeb/employee/api/v1/informations")
                    //.request().put(Entity.entity(input, MediaType.APPLICATION_JSON), Response.class);
            //GET Request
            final Response response = client
                    .target("https://localhost:7002/VaquarKhanWeb/employee/api/v1/informations")
                    .request().get();




            if (response.getStatus() != HttpStatus.OK.value()) { throw new RuntimeException("Failed : HTTP error code : "
                    + response.getStatus()); }
            String output = response.readEntity(String.class);
            System.out.println("Output from Server .... \n");
            System.out.println(output);
            client.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}