system: Linux mars.sprixweb.com 3.10.0-1160.119.1.el7.x86_64 #1 SMP Tue Jun 4 14:43:51 UTC 2024 x86_64

cmd: 

<?xml version="1.0"?>
<doc>
  <parent>
    <discarded>discarded</discarded>
    <preserved/>
    This text node must be discarded
    <discarded>discarded</discarded>
    <preserved>
      content1
      <child1/>
      <child2>content2</child2>
      <preserved>too</preserved>
      <child2>content3</child2>
      <preserved/>
      <child2>content4</child2>
      <preserved/>
      <child2>content5</child2>
      content6
    </preserved>
    This text node must be discarded
    <discarded>discarded</discarded>
    This text node must be discarded
    <preserved/>
    This text node must be discarded
    <preserved/>
    This text node must be discarded
    <discarded>discarded</discarded>
    This text node must be discarded
  </parent>
</doc>