Test case:

@RequestScoped
public class TestVarargs {
public void varargsMethod(String... strings) {}
}

public class TestClass {
@Inject
TestVarargs testVarargs;

public void runTest()

{ testClass(testVarargs.getClass()); testClass(TestVarargs.class); }

private void testClass(Class<?> clazz) {
for (Method m : clazz.getMethods()) {
if (m.getName().equals("varargsMethod"))

{ System.out.println(clazz + " : " + m + " : " + m.isVarArgs()); }

}
}
}

Prints:
class TestVarargs$Proxy$$$_WeldClientProxy : public void TestVarargs$Proxy$$$_WeldClientProxy.varargsMethod(java.lang.String[]) : false
class TestVarargs : public void TestVarargs.varargsMethod(java.lang.String[]) : true

The method generated in Weld proxy class is not a varargs method while the original one was. This breaks proper method lookup in tools that use reflection - in my case it was ZK EL resolver: for ${bean.method('String arg')} where signature is method(String...) there was proper code to handle a varargs call but only if the method was indeed declared as Method.isVarargs(), which was not the case when ${bean} was a Weld proxy.