Sample of usages:

Method
    defineClass(String, byte[], int, int, ClassLoader, ProtectionDomain)
Found usages (5 usages found)
    Production (5 usages found)
        jdk (5 usages found)
            java.lang.invoke (1 usage found)
                BoundMethodHandle.java (1 usage found)
                    582UNSAFE.defineClass(className, classFile, 0, classFile.length,
            java.lang.reflect (1 usage found)
                Proxy.java (1 usage found)
                    538Class<?> pc = UNSAFE.defineClass(proxyName, proxyClassFile,
            jdk.internal.reflect (1 usage found)
                ClassDefiner.java (1 usage found)
                    63return unsafe.defineClass(name, bytes, off, len, newLoader, null);
            jdk.jfr.internal (1 usage found)
                SecuritySupport.java (1 usage found)
                    366return unsafe.defineClass(name, bytes, 0, bytes.length, classLoader, null);
            sun.misc (1 usage found)
                Unsafe.java (1 usage found)
                    822return theInternalUnsafe.defineClass(name, b, off, len, loader, protectionDomain);