Remove unused imports, raw types and some deprecated method calls..

broker/src/main/java/io/moquette/spi/impl/security/DBAuthenticator.java

@@ -22,7 +22,6 @@ public class DBAuthenticator implements IAuthenticator {
 
     private static final Logger LOG = LoggerFactory.getLogger(DBAuthenticator.class);
 
-    private final String sqlQuery;
     private final MessageDigest messageDigest;
     private final PreparedStatement preparedStatement;
 
@@ -44,7 +43,6 @@ public class DBAuthenticator implements IAuthenticator {
      */
     public DBAuthenticator(String driver, String jdbcUrl, String sqlQuery, String digestMethod){
 
-        this.sqlQuery = sqlQuery;
         try {
             Class.forName(driver);
             final Connection connection = DriverManager.getConnection(jdbcUrl);

broker/src/main/java/io/moquette/spi/impl/security/ResourceAuthenticator.java

@@ -17,7 +17,6 @@ package io.moquette.spi.impl.security;
 
 import io.moquette.server.config.IResourceLoader;
 import io.moquette.spi.security.IAuthenticator;
-import org.apache.commons.codec.binary.Hex;
 import org.apache.commons.codec.digest.DigestUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;