get_property(<variable>
  <GLOBAL             |
  DIRECTORY [<dir>]  |
  TARGET    <target> |
  SOURCE    <source>
  [DIRECTORY <dir> | TARGET_DIRECTORY <target>] |
  INSTALL   <file>   |
  TEST      <test>
  [DIRECTORY <dir>] |
  CACHE     <entry>  |
  VARIABLE           >
  PROPERTY <name>
[SET | DEFINED | BRIEF_DOCS | FULL_DOCS])