java.lang.UnsupportedOperationException: This parser does not support specification “null“ version “

编译OpenJDK8，遇到错误：

Generating jfrEventClasses.hpp
java.lang.UnsupportedOperationException: This parser does not support specification "null" version "null"
        at javax.xml.parsers.SAXParserFactory.setSchema(SAXParserFactory.java:394)
        at build.tools.jfr.GenerateJfrFiles$Metadata.<init>(GenerateJfrFiles.java:114)
        at build.tools.jfr.GenerateJfrFiles.main(GenerateJfrFiles.java:43)

需要复制xerces.jar到编译的jre/lib/ext目录下。具体参考：

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