Is there a replacement library for CORBA in JDK 11

You can definitely take a look at javaee/glassfish-corba. The documented home page reads -

The GlassFish ORB complies with the CORBA 2.3.1 specification, and with the CORBA 3.0 specifications for the Interoperable Name Service and Portable Interceptors. It includes both IDL and RMI-IIOP support. The GlassFish ORB has an open, extensible architecture that supports flexible configuration and extension through an open SPI.

Further what shall also interest developers, from the JEP itself -

The risks of removing the java.corba module are:

1. CORBA implementations will not compile or run if they include only a subset of the "endorsed" CORBA APIs and expect the JDK to provide the remainder.

2. Applications and CORBA implementations that use RMI-IIOP will not compile or run. The RMI-IIOP packages (javax.rmi and javax.rmi.CORBA) are located in the java.corba module and tied to the CORBA implementation therein, so there will be no RMI-IIOP support in Java SE once java.corba is removed.

3. Applications and CORBA implementations that use the javax.activity package will not compile or run. This package is located in the java.corba module and tied to the CORBA implementation therein, so there will be no support in Java SE once java.corba is removed.

and further down there

• The transition of stewardship of Java EE from the JCP to the Eclipse

Foundation includes the GlassFish implementation of CORBA and RMI-IIOP.

additionally,

• The "CORBA interop package" if required is implemented along with the artifact javax.transaction : javax.transaction-api.

I haven't moved to Java 11 yet but I always had problems with the Java CORBA implementation anyway as it was incomplete and didn't support all the Object methods defined in the standards, didn't support ssliop, etc. etc. I always replaced it by placing th JacORB OMG jar in the endorsed directory and setting the system property to pont to the JacORB orb:

-Dorg.omg.CORBA.ORBClass=org.jacorb.orb.ORB -Dorg.omg.CORBA.ORBSingletonClass=org.jacorb.orb.ORBSingleton

BTW. I do not agree that ""There is no significant interest in developing modern applications with CORBA in Java" after all what is J2EE sitting on?

this dependency could be used in JDK11

        <dependency>
            <groupId>org.glassfish.corba</groupId>
            <artifactId>glassfish-corba-omgapi</artifactId>
            <version>4.2.1</version>
        </dependency>