Always unwrap old initialize methos

If these are delegated or wrapped by profiling, we will fail type
comparisons later on. Those comparisons are fragile, but for now
this is the simplest fix.

Fixes jruby#8148

core/src/main/java/org/jruby/java/proxies/ConcreteJavaProxy.java

@@ -211,7 +211,7 @@ public static class StaticJCreateMethod extends JavaMethodNBlock {
         StaticJCreateMethod(RubyModule implClass, Constructor<? extends ReifiedJavaProxy> javaProxyConstructor, DynamicMethod oldinit) {
             super(implClass, PUBLIC, "__jcreate_static!");
             this.withBlock = javaProxyConstructor;
-            this.oldInit = oldinit;
+            this.oldInit = oldinit == null ? oldinit : oldinit.getRealMethod(); // ensure we don't use a wrapper (jruby/jruby#8148)
         }
 
         @Override
@@ -374,7 +374,7 @@ public SplitCtorData splitInitialized(RubyClass base, IRubyObject[] args, Block
         final String name = base.getClassConfig().javaCtorMethodName;
         final CacheEntry methodEntry = base.searchWithCache(name);
         final boolean isLateral = isClassOrIncludedPrependedModule(methodEntry.sourceModule, base);
-        DynamicMethod method = methodEntry.method;
+        DynamicMethod method = methodEntry.method.getRealMethod(); // ensure we don't use a wrapper (jruby/jruby#8148)
         if (method instanceof StaticJCreateMethod) method = ((StaticJCreateMethod) method).oldInit;
 
         // jcreate is for nested ruby classes from a java class