There are two ways to write lambdas that contain single statement, but one is definitely more compact and readable than the other.

Noncompliant Code Example

x -> {System.out.println(x+1);}
(a, b) -> { return a+b; }

Compliant Solution

x -> System.out.println(x+1)
(a, b) -> a+b    //For return statement, the return keyword should also be dropped