Docker container JVM heap not applying

The environment variables:
NIFI_JVM_HEAP_INIT
NIFI_JVM_HEAP_MAX
do not get set properly once the container is running.
 
For example, when setting these variables in the docker run command:
docker run -d -p 8080:8080 -e NIFI_JVM_HEAP_INIT=2g -e NIFI_JVM_HEAP_MAX=2g apache/nifi:1.9.2
then checking http://localhost:8080/nifi-api/system-diagnostics shows that totalHeap and maxHeap are set to the default 512mb. Also exec-ing into the container and looking at the bootstrap.conf shows that java.arg.2 and java.arg.3 did not get updated.