To make the Java console run again on older Firmwares,
edit /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/jre/lib/security/java.security
and allow MD5 Algorythm again:
#jdk.jar.disabledAlgorithms=MD2, MD5, RSA keySize < 1024, DSA keySize < 1024
jdk.jar.disabledAlgorithms=MD2, RSA keySize < 1024, DSA keySize < 1024