code: public org.tensorflow.framework.FunctionDefLibrary getLibrary() {
      return library_ == null ? org.tensorflow.framework.FunctionDefLibrary.getDefaultInstance() : library_;
    }
docs: <pre>
  EXPERIMENTAL. DO NOT USE OR DEPEND ON THIS YET.
  "library" provides user-defined functions.
  Naming:
  * library.function.name are in a flat namespace.
  NOTE: We may need to change it to be hierarchical to support
  different orgs. E.g.,
  { "/google/nn", { ... }},
  { "/google/vision", { ... }}
  { "/org_foo/module_bar", { ... }}
  map&lt;string, FunctionDefLib&gt; named_lib;
  * If node[i].op is the name of one function in "library",
  node[i] is deemed as a function call. Otherwise, node[i].op
  must be a primitive operation supported by the runtime.
  Function call semantics:
  * The callee may start execution as soon as some of its inputs
  are ready. The caller may want to use Tuple() mechanism to
  ensure all inputs are ready in the same time.
  * The consumer of return values may start executing as soon as
  the return values the consumer depends on are ready.  The
  consumer may want to use Tuple() mechanism to ensure the
  consumer does not start until all return values of the callee
  function are ready.
  </pre>
  
  <code>optional .tensorflow.FunctionDefLibrary library = 2;</code>