New in version 3.12.1.
Calls to find_package(<PackageName>) will search in prefixes specified by the <PackageName>_ROOT CMake variable, where <PackageName> is the name given to the find_package() call and _ROOT is literal. For example, find_package(Foo) will search prefixes specified in the Foo_ROOT CMake variable (if set). See policy CMP0074.
This variable may hold a single prefix or a semicolon-separated list of multiple prefixes.
See also the <PackageName>_ROOT environment variable.
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Licensed under the BSD 3-clause License.
https://cmake.org/cmake/help/v3.19/variable/PackageName_ROOT.html