ADDITIONAL SYSTEM INFORMATION :
Linux 64 bit
Linux 4.15.0-39-generic #42-Ubuntu SMP Tue Oct 23 15:48:01 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

java version "1.8.0_192"
Java(TM) SE Runtime Environment (build 1.8.0_192-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.192-b12, mixed mode)


A DESCRIPTION OF THE PROBLEM :
The following code snippet reports compilation error:
package my;

import java.util.Comparator;

public class CheckJavaCompileError {
    private static final Comparator<String> MY_COMPARATOR = Comparator.comparing(lambdaVar -> lambdaVar);

    public CheckJavaCompileError() {
        return;
    }
}

Error:(9, 9) java: variable lambdaVar might not have been initialized

REGRESSION : Last worked in version 8u192

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Put code snippet into a file and compile it

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Code successfully compiled
ACTUAL -
Compilation reports error:
Error:(9, 9) java: variable lambdaVar might not have been initialized

---------- BEGIN SOURCE ----------
package my;

import java.util.Comparator;

public class CheckJavaCompileError {
    private static final Comparator<String> MY_COMPARATOR = Comparator.comparing(lambdaVar -> lambdaVar);

    public CheckJavaCompileError() {
        return;
    }
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Avoid using return statement in constructor

FREQUENCY : always