(cs) Charset.availableCharsets throws NPE if "non-standard" charset is not present

Charset.availableCharsets throws NullPointerException if any of the charsets listed in StandardCharsets is not present (all "standard" charsets, as listed in java.nio.charset.Charsets, are persent)

/opt/my/usg169/space/export/xxx/build/tests/image/bin/java
AvailableCharsetNames
Exception in thread "main" java.lang.NullPointerException
       at java.nio.charset.Charset.put(Charset.java:549)
       at java.nio.charset.Charset.access$300(Charset.java:272)
       at java.nio.charset.Charset$4.run(Charset.java:587)
       at java.nio.charset.Charset$4.run(Charset.java:582)
       at java.security.AccessController.doPrivileged(Native Method)
       at java.nio.charset.Charset.availableCharsets(Charset.java:581)
       at AvailableCharsetNames.main(AvailableCharsetNames.java:17)

Should I be expecting at least "US-ASCII" as one of the entries in
availableCharsets() ?