<idea-plugin>
    <id>com.intellij.myPlugin</id>

  <depends>com.intellij</depends>
  <depends>com.intellij.modules.vcs</depends>
  <depends>com.intellij.custom</depends>
  <depends><error descr="Cannot resolve plugin com.intellij.xxx">com.intellij.xxx</error></depends>


  <depends config-file="optional.xml">com.intellij</depends>
  <depends config-file="<error descr="Cannot resolve file 'INVALID_VALUE'">INVALID_VALUE</error>">com.intellij</depends>
</idea-plugin>