You Do Need power plug adapter while traveling from Saint Barthélemy to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in Saint Barthélemy are C and E. This is how they look like.

Saint Barthélemy

In Saint Barthélemy, outlets of type C and E are in use.

Type C

Type E

Sri Lanka

In Sri Lanka, outlets of type G are in use.

Type G