[MC-248694] An empty generator-settings string crashes the server when starting up

In a lot of servers prior to 1.18.2, the `generator-settings` string is empty since it is not needed. However, from 1.18.2, the server needs this field filled in - often with a simple JSON string such as `{}`, otherwise it will crash:

[15:16:23] [ServerMain/ERROR]: Failed to start the minecraft server
com.google.gson.JsonParseException: java.io.EOFException: End of input at line 1 column 1 path $
    at ajc.a(SourceFile:505) ~[server-1.18.2-pre1.jar:?]
    at ajc.a(SourceFile:555) ~[server-1.18.2-pre1.jar:?]
    at ajc.a(SourceFile:551) ~[server-1.18.2-pre1.jar:?]
    at ajc.a(SourceFile:559) ~[server-1.18.2-pre1.jar:?]
    at ada.a(SourceFile:108) ~[server-1.18.2-pre1.jar:?]
    at ada.a(SourceFile:128) ~[server-1.18.2-pre1.jar:?]
    at acx.<init>(SourceFile:84) ~[server-1.18.2-pre1.jar:?]
    at acx.a(SourceFile:91) ~[server-1.18.2-pre1.jar:?]
    at acy.<init>(SourceFile:12) ~[server-1.18.2-pre1.jar:?]
    at net.minecraft.server.Main.main(SourceFile:104) ~[server-1.18.2-pre1.jar:?]
    at net.minecraft.bundler.Main.lambda$run$0(Main.java:54) ~[?:?]
    at java.lang.Thread.run(Thread.java:833) [?:?]
Caused by: java.io.EOFException: End of input at line 1 column 1 path $
    at com.google.gson.stream.JsonReader.nextNonWhitespace(JsonReader.java:1395) ~[gson-2.8.9.jar:?]
    at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:548) ~[gson-2.8.9.jar:?]
    at com.google.gson.stream.JsonReader.peek(JsonReader.java:424) ~[gson-2.8.9.jar:?]
    at com.google.gson.internal.bind.TypeAdapters$27.read(TypeAdapters.java:661) ~[gson-2.8.9.jar:?]
    at com.google.gson.internal.bind.TypeAdapters$27.read(TypeAdapters.java:655) ~[gson-2.8.9.jar:?]
    at com.google.gson.internal.bind.TypeAdapters$33$1.read(TypeAdapters.java:866) ~[gson-2.8.9.jar:?]
    at ajc.a(SourceFile:503) ~[server-1.18.2-pre1.jar:?]

I've attached a server.properties file with an example setup.