Update niworkflows/interfaces/registration.py

Co-Authored-By: Chris Markiewicz <[email protected]>

Author: tsalo

niworkflows/interfaces/registration.py

@@ -353,7 +353,7 @@ class EstimateReferenceImageInputSpec(BaseInterfaceInputSpec):
                                    'are provided, they are assumed '
                                    'to represent multiple echoes '
                                    'from the same run.'))
-    sbref_file = InputMultiPath(File(exists=True),
+    sbref_file = InputMultiObject(File(exists=True),
                                 desc=("Single band reference image. "
                                       "If multiple files are provided, "
                                       "they are assumed to represent "