Add spec_like support to dataclass_array

PiperOrigin-RevId: 592844806

Author: Conchylicultor

CHANGELOG.md

@@ -23,6 +23,8 @@ To release a new version (e.g. from `1.0.0` -> `2.0.0`):
 
 ## [Unreleased]
 
+*   Fix `etree.spec_like` support
+
 ## [1.5.1] - 2023-08-30
 
 *   Fix look_at compatibility with pytorch

dataclass_array/array_dataclass.py

@@ -1103,6 +1103,9 @@ def is_value_missing(self) -> bool:
       # In `jax/_src/api_util.py` for `flatten_axes`, jax set all values to a
       # dummy sentinel `object()` value.
       return True
+    elif isinstance(self.value, enp.ArraySpec):
+      # `etree.spec_like` compatibility
+      return True
     elif (
         isinstance(self.value, DataclassArray) and not self.value._array_fields  # pylint: disable=protected-access
     ):