===
$ cat NITest.java
public class NITest {
    public static void main(String[] args) throws java.net.SocketException {
        java.net.NetworkInterface.getNetworkInterfaces();
    }
}
$ javac NITest.java
$ java -Xcheck:jni NITest
WARNING: JNI local refs: 33, exceeds capacity: 32
        at java.net.NetworkInterface.getAll(Native Method)
        at java.net.NetworkInterface.getNetworkInterfaces(NetworkInterface.java:343)
        at NITest.main(NITest.java:5)
===

This is the same issue as JDK-8187450, but the relevant code has been refactored since JDK11, and so the fix will be different (I.e. the JDK11 fix will not be a direct backport from trunk). This bug is intended to be for Trunk.