code: @Override
      public boolean sqlMapUpdateByExampleSelectiveElementGenerated(XmlElement element, IntrospectedTable introspectedTable) {
          // 清空
          XmlElement answer = new XmlElement("update");
          answer.addAttribute(new Attribute("id", introspectedTable.getUpdateByExampleSelectiveStatementId()));
          answer.addAttribute(new Attribute("parameterType", "map"));
  
          commentGenerator.addComment(answer);
  
          StringBuilder sb = new StringBuilder();
          sb.append("update ");
          sb.append(introspectedTable.getAliasedFullyQualifiedTableNameAtRuntime());
          answer.addElement(new TextElement(sb.toString()));
  
          // selective
          answer.addElement(new TextElement("SET"));
          answer.addElement(this.generateSetsSelective(ListUtilities.removeGeneratedAlwaysColumns(introspectedTable.getAllColumns())));
  
          answer.addElement(XmlElementGeneratorTools.getUpdateByExampleIncludeElement(introspectedTable));
  
          XmlElementTools.replaceXmlElement(element, answer);
  
          return super.sqlMapUpdateByExampleSelectiveElementGenerated(element, introspectedTable);
      }
docs: updateByExampleSelective
  具体执行顺序 http://www.mybatis.org/generator/reference/pluggingIn.html
  @param element
  @param introspectedTable
  @return