Add JdbcUserDetailsManager(DataSource) constructor

Fixes: gh-5512

core/src/main/java/org/springframework/security/provisioning/JdbcUserDetailsManager.java

@@ -37,6 +37,7 @@ import org.springframework.util.Assert;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
+import javax.sql.DataSource;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
@@ -122,6 +123,13 @@ public class JdbcUserDetailsManager extends JdbcDaoImpl implements UserDetailsMa
 
 	private UserCache userCache = new NullUserCache();
 
+	public JdbcUserDetailsManager() {
+	}
+
+	public JdbcUserDetailsManager(DataSource dataSource) {
+		setDataSource(dataSource);
+	}
+
 	// ~ Methods
 	// ========================================================================================================