Launching a server with the -Xms or -Xmx launch options doesn't work

Launching the 1.14 Pre-Release 2 server jar with the options "-Xms" or "-Xmx" using a batch file to specify RAM allocation does not launch the server, and gives this error:

Failed to start the minecraft server joptsimple.UnrecognizedOptionException: X is not a recognized option at joptsimple.OptionException.unrecognizedOption(OptionException.java:108) ~[server.jar:?] at joptsimple.OptionParser.validateOptionCharacters(OptionParser.java:633) ~[server.jar:?] at joptsimple.OptionParser.handleShortOptionCluster(OptionParser.java:528) ~[server.jar:?] at joptsimple.OptionParser.handleShortOptionToken(OptionParser.java:523) ~[server.jar:?] at joptsimple.OptionParserState$2.handleArgument(OptionParserState.java:59) ~[server.jar:?] at joptsimple.OptionParser.parse(OptionParser.java:396) ~[server.jar:?] at net.minecraft.server.MinecraftServer.main(SourceFile:879) [server.jar:?]

Removing the -Xms or -Xmx tags will cause the server to be launched as normal, with the default RAM allocation.

Tested on two systems, same result.