fix javadoc warning

src/main/java/com/imyeyu/spring/handler/GsonHandler.java

@@ -19,6 +19,12 @@ import java.sql.SQLException;
  */
 public class GsonHandler extends BaseTypeHandler<JsonElement> {
 
+	/**
+	 * 创建 Gson 类型处理器
+	 */
+	public GsonHandler() {
+	}
+
 	@Override
 	public void setNonNullParameter(PreparedStatement ps, int i, JsonElement parameter, JdbcType jdbcType) throws SQLException {
 		ps.setString(i, parameter.toString());