The new 1Z0-819 certification is the combination of the old existing ones (1Z0-815 & 1Z0-816) together.
OCP Java SE 11 Programmer I - Study guide for 1Z0-815
Welcome to Java
Java Building Blocks
Java Operators
Making Decisions
Core Java APIs
Lambdas and Functional Interfaces
Methods and Encapsulation
Class Design
Advanced Class Design
Exceptions
Java Modules