Java Jasperreport库版本6.17.0在PDF导出时产生错误

我基于Jasperreport库重新编译了我们的应用程序，并得到一个错误，调用PDF导出

java.lang.NullPointerException
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at net.sf.jasperreports.engine.util.JRClassLoader.loadClassForRealName(JRClassLoader.java:190)
at net.sf.jasperreports.engine.util.JRClassLoader.loadClassForName(JRClassLoader.java:148)
at net.sf.jasperreports.engine.util.JRSingletonCache.createInstance(JRSingletonCache.java:88)
at net.sf.jasperreports.engine.util.JRSingletonCache.getCachedInstance(JRSingletonCache.java:77)
at net.sf.jasperreports.engine.export.JRPdfExporter.getPdfProducerFactory(JRPdfExporter.java:735)
at net.sf.jasperreports.engine.export.JRPdfExporter.createPdfProducer(JRPdfExporter.java:806)
at net.sf.jasperreports.engine.export.JRPdfExporter.initExport(JRPdfExporter.java:704)
at net.sf.jasperreports.engine.export.JRPdfExporter.exportReport(JRPdfExporter.java:665)
at org.wgsoftpro.reposerver.SetReport.OutputReport(SetReport.java:770)
at org.wgsoftpro.reposerver.CreateReport.run(CreateReport.java:598)
at org.apache.catalina.core.AsyncContextImpl$RunnableWrapper.run(AsyncContextImpl.java:602)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)

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它在6.16版本中运行良好。我刚刚在pom.xml中将6.16改为6.17。任何建议都将得到批准

解决，如果在read.me版本中提到新规则会更好。我们根据需要替换了default.jasperreports.properties。现在是绳子

net.sf.jasperreports.export.pdf.producer.factory=net.sf.jasperreports.export.pdf.classic.ClassicPdfProducerFactory

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必须显示在default.jasperreports.properties文件中，才能获得加载相应类的库可能性。

非常感谢，很好的提示。第一次尝试调试时没有注意到。详情尚待回答