Fix bulk importer's multivalued dates import

• Create a Whatever doctype in Studio inheriting from File, with a multivalued dates field called someDates
• Use the following metadata.properties file for content import:

  ecm\:primaryType=Whatever
  whatever\:someDates=2020-26-10T09:39:43.00Z|2030-26-10T09:39:43.00Z|2040-26-10T09:39:43.00Z
  

• Import data

=> Result: whatever:someDates field contains 3 null entries
=> Expected: dates should be properly set