In an attempt to make our documentation HTML5 compliant, we want to clean up all the warnings reported by tidy against our documentation.

I am grouping these into one issue to avoid the need of reviewing 3 separate issues.

 ---- begin processing java.base/java/lang/classfile/components/CodeStackTracker.html
java.base/java/lang/classfile/components/CodeStackTracker.html:107:2: Warning: trimming empty <p>
 ---- begin processing java.base/java/lang/classfile/package-summary.html
java.base/java/lang/classfile/package-summary.html:99:2: Warning: trimming empty <p>
java.base/java/lang/classfile/package-summary.html:618:2: Warning: trimming empty <p>
java.base/java/lang/classfile/package-summary.html:755:2: Warning: trimming empty <p>
 ---- begin processing java.base/java/text/MessageFormat.html
java.base/java/text/MessageFormat.html:434:2: Warning: trimming empty <p>
 ---- begin processing java.base/javax/security/auth/Subject.html
java.base/javax/security/auth/Subject.html:206:8: Warning: missing </a> before <a>
java.base/javax/security/auth/Subject.html:208:98: Warning: discarding unexpected </a>

Additionally there are a few reports of broken links and some missing files in the generated documentation

docs/api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnFailure.html:245: id not found: docs/api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnFailure.html#TreeStructure
docs/api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnSuccess.html:242: id not found: docs/api/java.base/java/util/concurrent/StructuredTaskScope.ShutdownOnSuccess.html#TreeStructure

Missing files: (2)
docs/api/java.base/java/lang/ref/package.html
    in docs/api/java.base/java/lang/foreign/Arena.html
    in docs/api/java.base/java/lang/foreign/MemorySegment.Scope.html
    in docs/api/java.base/java/lang/foreign/MemorySegment.html
    in docs/api/java.base/java/lang/foreign/SymbolLookup.html
docs/api/java.base/java/net/spi/doc-files/net-properties.html
    in docs/api/java.base/java/net/spi/InetAddressResolver.LookupPolicy.html