question: initializes the default union filesystem instance as a unionfilesystem . if it 's not initialized , then initialize it , otherwise verify if the type of the instance is correct . concode_field_sep FileSystem defaultNativeFileSystem concode_elem_sep FileSystem defaultJavaIoFileSystem concode_elem_sep FileSystem defaultUnionFileSystem concode_field_sep FileSystem getNativeFileSystem concode_elem_sep FileSystem getJavaIoFileSystem concode_elem_sep FileSystem getZipFileSystem
target: FileSystem function ( Map < PathFragment , FileSystem > arg0 , FileSystem arg1 ) { if ( defaultUnionFileSystem == null ) { defaultUnionFileSystem = new UnionFileSystem ( arg0 , arg1 ) ; } else { Verify . verify ( defaultUnionFileSystem instanceof UnionFileSystem ) ; } return defaultUnionFileSystem ; }