static initializers of StartupMessage cause blocking calls

[62mkv]

Bug Report

Versions

• Driver: 0.8.0.RELEASE
• Database: 11.7
• Java: 8.0.172
• OS: Windows 10

Current Behavior

Initialization blocks of static variables in StartupMessage might issue blocking calls, which might lead to BlockHound enabled tests failing, as in:

Caused by: reactor.blockhound.BlockingOperationError: Blocking call! java.io.FileInputStream#readBytes
    at java.io.FileInputStream.readBytes(FileInputStream.java)
    at java.io.FileInputStream.read(FileInputStream.java:255)
    at java.io.BufferedInputStream.fill(BufferedInputStream.java:246)
    at java.io.BufferedInputStream.read(BufferedInputStream.java:265)
    at java.io.DataInputStream.readByte(DataInputStream.java:265)
    at java.time.zone.TzdbZoneRulesProvider.load(TzdbZoneRulesProvider.java:162)
    at java.time.zone.TzdbZoneRulesProvider.<init>(TzdbZoneRulesProvider.java:113)
    at java.time.zone.ZoneRulesProvider$1.run(ZoneRulesProvider.java:157)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.time.zone.ZoneRulesProvider.<clinit>(ZoneRulesProvider.java:144)
    at java.time.ZoneRegion.ofId(ZoneRegion.java:120)
    at java.time.ZoneId.of(ZoneId.java:411)
    at java.time.ZoneId.of(ZoneId.java:359)
    at java.time.ZoneId.of(ZoneId.java:315)
    at java.util.TimeZone.toZoneId(TimeZone.java:556)
    at java.time.ZoneId.systemDefault(ZoneId.java:274)
    at io.r2dbc.postgresql.message.frontend.StartupMessage.<clinit>(StartupMessage.java:58)

Steps to reproduce

any code, that will execute r2dbc-postgresql query, wrapped with BlockHound.install()

Expected behavior/code

No BlockHound-caused exceptions

Possible Solution

As has been suggested by @mp911de :

Interestingly, switching to TimeZone.getDefault().getID() returns the same result but without loading the timezone database.

Additional context