Gittern\Entity\GitObject\Tree::getSha PHP Method

    public function getSha()
    {
        return $this->sha;
    }

 protected function writeTree(Tree $tree, Writer $writer)
 {
     $sha = $tree->getSha();
     if (strlen($sha) != 40) {
         throw new NotPersistedException("Tree referred to by commit is not persisted yet.");
     }
     $writer->writeString8("tree ");
     $writer->writeString8($sha);
     $writer->writeString8("\n");
 }