overrideGeneratedOutputDirectory function
Overrides the generated directory name.
This is interpreted as a relative path under the cacheDir.
Implementation
void overrideGeneratedOutputDirectory(String path) {
if (_generatedOutputDirectory != 'generated') {
throw StateError('You can only override the generated dir once.');
} else if (_generatedOutputDirectoryIsLocked) {
throw StateError(
'Attempted to override the generated dir after it was locked.');
} else if (!p.isRelative(path)) {
throw StateError('Only relative paths are accepted for the generated dir '
'but got `$path`.');
}
_generatedOutputDirectory = path;
}