APT_ORACLE_PRESERVE_BLANKS = TRUE generating spaces

[NigeGriff]

A varchar2(50) source column containing a string value less than 50 in length with no trailing spaces when loaded to target oracle table where the target column is defined as varchar2(50) is padding out the string value with trailing spaces to 50 characters in length.

My understanding was that when APT_ORACEL_PRESERVE_BLANKS is set to TRUE then only existing trailing spaces would be preserved and additional trailing spaces would not be generated to pad out the string to the maximun length of 50.

Is this the expected behaviopur of the environmental variable?