安装插件提示一下错误，请帮忙看下，这个问题要怎么解决

2018-06-19 15:26:41,603 INFO o.j.r.JARSourceHTTP: Requesting https://jmeter-plugins.org/repo/?installID=windows_7-6098cd26cb66484fe7be1a382789467e-gui

2018-06-19 15:26:42,923 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for text/html is org.apache.jmeter.protocol.http.parser.LagartoBasedHtmlParser
2018-06-19 15:26:42,923 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for application/xhtml+xml is org.apache.jmeter.protocol.http.parser.LagartoBasedHtmlParser
2018-06-19 15:26:42,924 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for application/xml is org.apache.jmeter.protocol.http.parser.LagartoBasedHtmlParser
2018-06-19 15:26:42,924 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for text/xml is org.apache.jmeter.protocol.http.parser.LagartoBasedHtmlParser
2018-06-19 15:26:42,924 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for text/vnd.wap.wml is org.apache.jmeter.protocol.http.parser.RegexpHTMLParser
2018-06-19 15:26:42,924 INFO o.a.j.p.h.s.HTTPSamplerBase: Parser for text/css is org.apache.jmeter.protocol.http.parser.CssParser
2018-06-19 15:26:43,385 INFO o.a.j.e.KeyToolUtils: keytool found at 'keytool'
2018-06-19 15:26:43,385 INFO o.a.j.p.h.p.ProxyControl: HTTP(S) Test Script Recorder SSL Proxy will use keys that support embedded 3rd party resources in file E:\apache-jmeter-4.0\apache-jmeter-4.0\bin\proxyserver.jks
2018-06-19 15:26:43,497 INFO o.a.j.s.FileServer: Default base='E:\apache-jmeter-4.0\apache-jmeter-4.0\bin'
2018-06-19 15:26:43,864 INFO o.a.j.s.SampleResult: Note: Sample TimeStamps are START times
2018-06-19 15:26:43,864 INFO o.a.j.s.SampleResult: sampleresult.default.encoding is set to ISO-8859-1
2018-06-19 15:26:43,865 INFO o.a.j.s.SampleResult: sampleresult.useNanoTime=true
2018-06-19 15:26:43,865 INFO o.a.j.s.SampleResult: sampleresult.nanoThreadSleep=5000
2018-06-19 15:26:44,843 INFO o.j.r.PluginManager: Plugins Status: [jpgc-plugins-manager=1.0.2, websocket-sampler=1.0.2-SNAPSHOT, jmeter-core=4.0, jmeter-ftp=4.0, jmeter-http=4.0, jmeter-jdbc=4.0, jmeter-jms=4.0, jmeter-junit=4.0, jmeter-java=4.0, jmeter-ldap=4.0, jmeter-mail=4.0, jmeter-mongodb=4.0, jmeter-native=4.0, jmeter-tcp=4.0, jmeter-components=4.0]
2018-06-19 15:26:44,844 INFO o.j.r.PluginManagerMenuItem: Plugins Manager has upgrades: [jpgc-plugins-manager]
2018-06-19 15:26:46,939 INFO o.a.j.u.JMeterUtils: Setting Locale to zh_CN
2018-06-19 15:26:54,339 INFO o.j.r.JARSourceHTTP: Downloading: https://search.maven.org/remotecontent?filepath=kg/apc/cmdrunner/2.2/cmdrunner-2.2.jar
2018-06-19 15:26:55,103 ERROR o.j.r.PluginManager: Failed to download cmdrunner>=2.2
javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.ssl.Alerts.getSSLException(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.SSLSocketImpl.fatal(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.Handshaker.fatalSE(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.Handshaker.fatalSE(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.ClientHandshaker.serverCertificate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.ClientHandshaker.processMessage(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.Handshaker.processLoop(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.Handshaker.process_record(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.SSLSocketImpl.readRecord(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.SSLSocketImpl.performInitialHandshake(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.SSLSocketImpl.startHandshake(Unknown Source) ~[?:1.8.0_91]
    at org.apache.http.conn.ssl.SSLSocketFactory.createLayeredSocket(SSLSocketFactory.java:573) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.conn.ssl.SSLSocketFactory.connectSocket(SSLSocketFactory.java:557) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.conn.ssl.SSLSocketFactory.connectSocket(SSLSocketFactory.java:414) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:180) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.conn.ManagedClientConnectionImpl.open(ManagedClientConnectionImpl.java:326) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.client.DefaultRequestDirector.tryConnect(DefaultRequestDirector.java:610) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:445) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.client.AbstractHttpClient.doExecute(AbstractHttpClient.java:835) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83) ~[httpclient-4.5.5.jar:4.5.5]
    at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:56) ~[httpclient-4.5.5.jar:4.5.5]
    at org.jmeterplugins.repository.JARSourceHTTP.execute(JARSourceHTTP.java:481) ~[jmeter-plugins-manager-1.0.2.jar:?]
    at org.jmeterplugins.repository.JARSourceHTTP.getJAR(JARSourceHTTP.java:386) ~[jmeter-plugins-manager-1.0.2.jar:?]
    at org.jmeterplugins.repository.PluginManager.applyChanges(PluginManager.java:167) [jmeter-plugins-manager-1.0.2.jar:?]
    at org.jmeterplugins.repository.PluginManagerDialog$4.run(PluginManagerDialog.java:226) [jmeter-plugins-manager-1.0.2.jar:?]
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.validator.PKIXValidator.doBuild(Unknown Source) ~[?:1.8.0_91]
    at sun.security.validator.PKIXValidator.engineValidate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.validator.Validator.validate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.validate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source) ~[?:1.8.0_91]
    ... 22 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.provider.certpath.SunCertPathBuilder.build(Unknown Source) ~[?:1.8.0_91]
    at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(Unknown Source) ~[?:1.8.0_91]
    at java.security.cert.CertPathBuilder.build(Unknown Source) ~[?:1.8.0_91]
    at sun.security.validator.PKIXValidator.doBuild(Unknown Source) ~[?:1.8.0_91]
    at sun.security.validator.PKIXValidator.engineValidate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.validator.Validator.validate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.validate(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.checkTrusted(Unknown Source) ~[?:1.8.0_91]
    at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(Unknown Source) ~[?:1.8.0_91]
    ... 22 more