Review Request: JDK-8211921,,AssertionError in MethodHandles$Lookup.defineClass

[Mandy Chung]

The assertion in Lookup::defineClass ensures that the resulting
Class is defined with the same loader in the same package in
the same protection domain as the lookup class.  When a class
is defined to the boot loader, its protection domain is set to
null which implies AllPermission but Class::getProtectionDomain
however does not guarantee to return the same PD instance.  Hence
the assertion may fail when 2+ threads are getting PD at the same
time.

This assertion is not strictly necessary and
test/jdk/java/lang/invoke/DefineClassTest.java verifies these
properties of the resulting Class.  I propose to remove this
assertion.

diff --git 
a/src/java.base/share/classes/java/lang/invoke/MethodHandles.java 
b/src/java.base/share/classes/java/lang/invoke/MethodHandles.java
--- a/src/java.base/share/classes/java/lang/invoke/MethodHandles.java
+++ b/src/java.base/share/classes/java/lang/invoke/MethodHandles.java
@@ -969,9 +969,6 @@
              ProtectionDomain pd = (loader != null) ? 
lookupClassProtectionDomain() : null;
              String source = "__Lookup_defineClass__";
              Class<?> clazz = 
SharedSecrets.getJavaLangAccess().defineClass(loader, cn, bytes, pd, 
source);
-            assert clazz.getClassLoader() == lookupClass.getClassLoader()
-                    && 
clazz.getPackageName().equals(lookupClass.getPackageName())
-                    && protectionDomain(clazz) == 
lookupClassProtectionDomain();
              return clazz;
          }

Mandy