ADDITIONAL SYSTEM INFORMATION :
openjdk version "11.0.4" 2019-07-16
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.4+11)
Eclipse OpenJ9 VM AdoptOpenJDK (build openj9-0.15.1, JRE 11 Windows 10 amd64-64-Bit Compressed References 20190717_282 (JIT enabled, AOT enabled)
OpenJ9 - 0f66c6431
OMR - ec782f26
JCL - fa49279450 based on jdk-11.0.4+11)

A DESCRIPTION OF THE PROBLEM :
Got an error compiling the following class.
Eclipse Compiler works fine.
Tested AdoptOpenJDK 11.0.4-hotspot and 11.0.4-openj9

C:\Shape\workspaces\eclipse\shape-ee8\shape-core-ee8\src\main\java\JavaBugTest.java:31: error: unreported exception Throwable; must be caught or declared to be thrown
                m2(m1(System::currentTimeMillis));
                     ^


public class JavaBugTest
{
interface Validator<X extends Throwable>
{
public void test() throws X;
}

// removing U -> compiles
// returning Object -> compiles
// returning T -> error!
// it seems the bug is related to this specific combination of generics
public static <T, U, X extends Throwable> T m1(Validator<X> v) throws X
    {
return null;
    }

public static <T> T m2(T t)
{
return null;
}

public static void main(String[] args)
{
// this one compiles
m1(System::currentTimeMillis);

// this one compiles
m2(JavaBugTest.<Object, Object, RuntimeException> m1(System::currentTimeMillis));

// error!
m2(m1(System::currentTimeMillis));
}
}

REGRESSION : Last worked in version 8u221

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
compile the class

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
compilation successful
ACTUAL -
C:\Shape\workspaces\eclipse\shape-ee8\shape-core-ee8\src\main\java\JavaBugTest.java:31: error: unreported exception Throwable; must be caught or declared to be thrown
                m2(m1(System::currentTimeMillis));
                     ^


---------- BEGIN SOURCE ----------
public class JavaBugTest
{
interface Validator<X extends Throwable>
{
public void test() throws X;
}

// removing U -> compiles
// returning Object -> compiles
// returning T -> error!
// it seems the bug is related to this specific combination of generics
public static <T, U, X extends Throwable> T m1(Validator<X> v) throws X
    {
return null;
    }

public static <T> T m2(T t)
{
return null;
}

public static void main(String[] args)
{
// this one compiles
m1(System::currentTimeMillis);

// this one compiles
m2(JavaBugTest.<Object, Object, RuntimeException> m1(System::currentTimeMillis));

// error!
m2(m1(System::currentTimeMillis));
}
}
---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
explicitly define generic types

FREQUENCY : always