Translate base64 name-decode errors to StreamReadException

[Sahana2524]

When a base64 XmlNameProcessor is configured, reading a name that is not valid base64 lets the decoder's exception escape the parser:

java.lang.IllegalArgumentException: Input byte[] should at least have 2 bytes for base64 bytes
    at java.base/java.util.Base64$Decoder.decode(...)
    at ...XmlNameProcessors$AlwaysOnBase64NameProcessor.decodeName(XmlNameProcessors.java:230)
    at ...deser.XmlTokenStream._decodeElementName(XmlTokenStream.java:786)
    at ...deser.FromXmlParser._nextToken(FromXmlParser.java:1421)

The base64 processors decode every incoming element/attribute name through java.util.Base64, which throws IllegalArgumentException on malformed input. That went uncaught, so callers guarding reads with catch (JacksonException) see a raw runtime exception instead.

The base64 processors in XmlNameProcessors now translate the decoder's IllegalArgumentException into a StreamReadException at the point of decode, so the failure is handled where it happens and cannot leak through any parser path (root-name decode in XmlTokenStream.initialize() or later names in _nextToken()). Valid names and the default passthrough processor are unchanged. Added regression tests in XmlNameEscapeTest for both the prefixed and always-on base64 processors.

[github-actions]

🧪 Code Coverage Report

Metric	Coverage	Change
Instructions	73.56%	📈 +0.030%
Branches	68.03%	📈 +0.000%

Coverage data generated from JaCoCo test results

[cowtowncoder]

Test makes sense and problem should be addressed. But not in "nextToken()" calls -- needs to be closer to the actual fail, NameProcessor must translate failures and not leak them through.

[Sahana2524]

Makes sense. Moved the translation into the base64 processors themselves: decodeName now wraps the decoder's IllegalArgumentException in a StreamReadException, and the parser-side catches are reverted. That covers both the root-name path and _nextToken() from the same place. Tests unchanged, full suite still passes.

[github-actions]

🧪 Code Coverage Report

Metric	Coverage	Change
Instructions	73.59%	📈 +0.040%
Branches	68.08%	📈 +0.000%

Coverage data generated from JaCoCo test results