I have the task to migrate from Braintree API to PayPal REST API and after spending half of the day I was so disappointed of their Java SDK quality that I'm ready to fight this migration in 1st place.

Basically:

1. Outdated API reference (java code samples) - some classe were replaced but reference still uses them

2. deprecated methods in their Java SDK without comments what should be used instead.

3. Multiple sdk_config.properties files not supported out of the box (this is very retarded, since they have sandbox)

PS: Braintree API is a dream for dev came true, imho