单个线程组里运行多个http请求和多个线程组运行时debug报错

[wangehwei]

`com.thoughtworks.xstream.io.StreamException:
at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:124)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.readRealEvent(AbstractPullReader.java:148)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.readEvent(AbstractPullReader.java:141)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.move(AbstractPullReader.java:118)
at com.thoughtworks.xstream.io.xml.AbstractPullReader.moveDown(AbstractPullReader.java:103)
at com.thoughtworks.xstream.io.xml.XppReader.(XppReader.java:63)
at com.thoughtworks.xstream.io.xml.AbstractXppDriver.createReader(AbstractXppDriver.java:54)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1321)
at com.thoughtworks.xstream.XStream.fromXML(XStream.java:1312)
at io.github.guojiaxing1995.easyJmeter.service.impl.CaseServiceImpl.debugCase(CaseServiceImpl.java:247)
at io.github.guojiaxing1995.easyJmeter.controller.v1.SocketIOServerHandler.caseDebug(SocketIOServerHandler.java:354)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)

at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)

Caused by: org.xmlpull.v1.XmlPullParserException: only whitespace content allowed before start tag and not t (position: START_DOCUMENT seen t... @1:2)
at io.github.xstream.mxparser.MXParser.parseProlog(MXParser.java:1528)
at io.github.xstream.mxparser.MXParser.nextImpl(MXParser.java:1406)
at io.github.xstream.mxparser.MXParser.next(MXParser.java:1104)
at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:109)
... 73 common frames omitted
`
有时候提示多个samples