If the following simple code is run from command line using JDK11 (seen in b12 al least) an NPE is thrown.

public class Test {
    public static void main(String... args) {
        System.out.println(
               java.lang.management.ManagementFactory.getPlatformMXBeans(
                        java.lang.management.BufferPoolMXBean.class
                )
        );
    }
}

Exception in thread "main" java.lang.NullPointerException
at java.management/sun.management.ManagementFactoryHelper.getBufferPoolMXBeans(ManagementFactoryHelper.java:345)
at java.management/java.lang.management.DefaultPlatformMBeanProvider$10.nameToMBeanMap(DefaultPlatformMBeanProvider.java:422)
at java.management/sun.management.spi.PlatformMBeanProvider$PlatformComponent.getMBeans(PlatformMBeanProvider.java:195)
at java.management/java.lang.management.ManagementFactory.lambda$getPlatformMXBeans$3(ManagementFactory.java:726)
at java.base/java.util.stream.ReferencePipeline$7$1.accept(ReferencePipeline.java:271)
at java.base/java.util.HashMap$ValueSpliterator.forEachRemaining(HashMap.java:1675)
at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:484)
at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
at java.management/java.lang.management.ManagementFactory.getPlatformMXBeans(ManagementFactory.java:727)
at Test.main(Test.java:4)