Nexus 3.3 may log messages such as these:
2017-04-19 01:27:59,918-0600 WARN [qtp608450668-367] *UNKNOWN org.sonatype.nexus.repository.maven.internal.proxy.MavenProxyFacet - Content not present for org/apache/geronimo/specs/geronimo-activation_1.0.2_spec/1.1/geronimo-activation_1.0.2_spec-1.1-sources.jar, throwing exception. 2017-04-19 01:28:00,441-0600 WARN [qtp608450668-367] *UNKNOWN org.sonatype.nexus.repository.maven.internal.proxy.MavenProxyFacet - Content not present for org/apache/geronimo/specs/geronimo-activation_1.0.2_spec/1.1/geronimo-activation_1.0.2_spec-1.1-sources.jar, throwing exception. 2017-04-19 01:28:13,342-0600 INFO [qtp608450668-367] *UNKNOWN org.sonatype.nexus.repository.httpclient.internal.HttpClientFacetImpl - Repository status for familysearch changed from AVAILABLE to UNAVAILABLE - reason java.net.SocketTimeoutException: Read timed out for http://nexus.a.fsglobal.net 2017-04-19 01:28:13,343-0600 WARN [qtp608450668-367] *UNKNOWN org.sonatype.nexus.repository.maven.internal.proxy.MavenProxyFacet - Content not present for org/apache/geronimo/specs/geronimo-activation_1.0.2_spec/1.1/geronimo-activation_1.0.2_spec-1.1-sources.jar, throwing exception. 2017-04-19 01:28:15,338-0600 WARN [qtp608450668-391] *UNKNOWN org.sonatype.nexus.repository.maven.internal.proxy.MavenProxyFacet - Content not present for org/apache/geronimo/specs/geronimo-activation_1.0.2_spec/1.1/geronimo-activation_1.0.2_spec-1.1-sources.jar, throwing exception. 2017-04-19 01:28:15,493-0600 WARN [qtp608450668-391] *UNKNOWN org.sonatype.nexus.repository.maven.internal.proxy.MavenProxyFacet - Content not present for org/apache/geronimo/specs/geronimo-activation_1.0.2_spec/1.1/geronimo-activation_1.0.2_spec-1.1-sources.jar, throwing exception.
Where did it throw the exception? What was the exception? "Content not present for" means nothing. What content where? On disk? In an http response from the proxy? Headers?
These log levels MAY have been overridden at the time in logback-overrides.xml, but these loggers should not prevent seeing a more useful log message:
<included> <logger name='remote.storage.outbound' level='DEBUG'/> <logger name='org.eclipse.jetty.http.HttpParser' level='ERROR'/> <logger name='org.apache.http' level='INFO'/> </included>