Trying to run logstash

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by com.headius.backport9.modules.Modules (file:/home/kingram/logstash-7.1.0/logstash-core/lib/jars/jruby-complete-9.2.7.0.jar) to field java.io.FileDescriptor.fd
WARNING: Please consider reporting this to the maintainers of com.headius.backport9.modules.Modules
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
Sending Logstash logs to /home/kingram/logstash-7.1.0/logs which is now configured via log4j2.properties
[2019-05-27T13:28:31,600][ERROR][org.logstash.Logstash ] java.lang.IllegalStateException: Logstash stopped processing because of an error: (LoadError) load error: ffi/ffi -- java.lang.NullPointerException: null
============== Environment
Raspbian 9 (Stretch)

$ echo $JAVA_HOME
/usr/lib/jvm/java-11-openjdk-armhf

$ java -version
openjdk version "11.0.3" 2019-04-16
OpenJDK Runtime Environment (build 11.0.3+1-Raspbian-1)
OpenJDK Server VM (build 11.0.3+1-Raspbian-1, mixed mode)