The Hadoop Properties section of the Job Designer allows you to specify properties (of the form key=value) to be passed to hadoop when submitting the job. Though the space character is a valid value it is trimmed upon submission and not assigned to the property (e.g. stream.map.output.field.separator= ). If the space is quoted (stream.map.output.field.separator=' ') a ValidationError is raised. The latter format is valid when passed to hadoop on the command line.
Define a Hadoop Property in the Job Designer with a space as the value.