A jaxp test failed once, the failure happened as the following process:
Jaxp library tried to load extended Charset, it called ServiceLoader.loadInstalled(CharsetProvider.class), in this function, it need to verifyModuleAccess, but CharsetProvider.class.getModule() returned a null, then NullPointerException was thrown at code memberModule.isExported(c.getPackageName(), currentModule);

The full stack trace is:
java.lang.NullPointerException
at jdk.internal.reflect.Reflection.verifyModuleAccess(java.base@9-ea/Reflection.java:209)
at java.util.ServiceLoader.checkModule(java.base@9-ea/ServiceLoader.java:364)
at java.util.ServiceLoader.<init>(java.base@9-ea/ServiceLoader.java:319)
at java.util.ServiceLoader.<init>(java.base@9-ea/ServiceLoader.java:351)
at java.util.ServiceLoader.loadInstalled(java.base@9-ea/ServiceLoader.java:1059)
at java.nio.charset.Charset$ExtendedProviderHolder$1.run(java.base@9-ea/Charset.java:435)
at java.nio.charset.Charset$ExtendedProviderHolder$1.run(java.base@9-ea/Charset.java:430)
at java.security.AccessController.doPrivileged(java.base@9-ea/Native Method)
at java.nio.charset.Charset$ExtendedProviderHolder.extendedProviders(java.base@9-ea/Charset.java:430)
at java.nio.charset.Charset$ExtendedProviderHolder.<clinit>(java.base@9-ea/Charset.java:427)
at java.nio.charset.Charset.lookupExtendedCharset(java.base@9-ea/Charset.java:450)
at java.nio.charset.Charset.lookup2(java.base@9-ea/Charset.java:480)
at java.nio.charset.Charset.lookup(java.base@9-ea/Charset.java:468)
at java.nio.charset.Charset.forName(java.base@9-ea/Charset.java:532)
at com.sun.org.apache.xml.internal.serializer.Encodings$EncodingInfos.findCharsetNameFor(java.xml@9-ea/Encodings.java:403)
at com.sun.org.apache.xml.internal.serializer.Encodings$EncodingInfos.findCharsetNameFor(java.xml@9-ea/Encodings.java:439)
at com.sun.org.apache.xml.internal.serializer.Encodings$EncodingInfos.loadEncodingInfo(java.xml@9-ea/Encodings.java:467)
at com.sun.org.apache.xml.internal.serializer.Encodings$EncodingInfos.<init>(java.xml@9-ea/Encodings.java:325)
at com.sun.org.apache.xml.internal.serializer.Encodings$EncodingInfos.<init>(java.xml@9-ea/Encodings.java:313)
at com.sun.org.apache.xml.internal.serializer.Encodings.<clinit>(java.xml@9-ea/Encodings.java:581)
at com.sun.org.apache.xalan.internal.xsltc.compiler.Output.parseContents(java.xml@9-ea/Output.java:190)
at com.sun.org.apache.xalan.internal.xsltc.compiler.Stylesheet.parseOwnChildren(java.xml@9-ea/Stylesheet.java:596)
at com.sun.org.apache.xalan.internal.xsltc.compiler.Stylesheet.parseContents(java.xml@9-ea/Stylesheet.java:558)
at com.sun.org.apache.xalan.internal.xsltc.compiler.Parser.createAST(java.xml@9-ea/Parser.java:402)
at com.sun.org.apache.xalan.internal.xsltc.compiler.XSLTC.compile(java.xml@9-ea/XSLTC.java:495)
at com.sun.org.apache.xalan.internal.xsltc.compiler.XSLTC.compile(java.xml@9-ea/XSLTC.java:580)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTemplates(java.xml@9-ea/TransformerFactoryImpl.java:1024)
at com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl.newTransformer(java.xml@9-ea/TransformerFactoryImpl.java:823)
at transform.BugDB12665704Test.getTransformer(BugDB12665704Test.java:130)
at transform.BugDB12665704Test.testSAPTransform(BugDB12665704Test.java:108)