Steps to reproduce

• Create a new ContentType
• Add `ezmatrix` field, configure it as follows
  • Name: Name with spaces
  • Identifier: Identifier with spaces
• Save ContentType - at this step everything is fine, no validation errors
• Go to Content
• Try to create an Content Item of the newly created ContentType (step 1)

Result

The following exception is thrown:

The name "Identifier with spaces" contains illegal characters. Names should start with a letter, digit or underscore and only contain letters, digits, numbers, underscores ("_"), hyphens ("-") and colons (":"). 

See attachment for the full stack trace.