Opening the NRTG window gives an exception if any of the configuration values contains a ; (semicolon) or a = (equals) character.

The following exception is shown:
java.lang.IllegalArgumentException
at org.opennms.netmgt.snmp.SnmpAgentConfig.parseProtocolConfigurationString(SnmpAgentConfig.java:81)
at org.opennms.nrtg.protocolcollector.snmp.internal.SnmpProtocolCollector.collect(SnmpProtocolCollector.java:103)
at Proxy0052687a_3360_4aa8_bc6b_6b19556d95d4.collect(Unknown Source)
at org.opennms.nrtg.nrtbroker.local.internal.NrtBrokerLocal.publishCollectionJob(NrtBrokerLocal.java:114)
at Proxy8fc8dcfb_de34_4986_bfd6_8004c33ae723.publishCollectionJob(Unknown Source)
at org.opennms.nrtg.web.internal.NrtController.nrtStart(NrtController.java:125)
at org.opennms.nrtg.web.internal.NrtServlet.doGet(NrtServlet.java:65)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.opennms.container.web.felix.base.internal.handler.ServletHandler.doHandle(ServletHandler.java:101)
at org.opennms.container.web.felix.base.internal.handler.ServletHandler.handle(ServletHandler.java:84)
at org.opennms.container.web.felix.base.internal.dispatch.ServletPipeline.handle(ServletPipeline.java:43)
at org.opennms.container.web.felix.base.internal.dispatch.InvocationFilterChain.doFilter(InvocationFilterChain.java:52)
at org.opennms.container.web.felix.base.internal.dispatch.HttpFilterChain.doFilter(HttpFilterChain.java:35)
at org.opennms.container.web.felix.base.internal.dispatch.FilterPipeline.dispatch(FilterPipeline.java:50)
at org.opennms.container.web.felix.base.internal.dispatch.Dispatcher.dispatch(Dispatcher.java:42)
at org.opennms.container.web.bridge.internal.DispatcherFilter.doFilter(DispatcherFilter.java:72)
at org.opennms.container.web.ProxyFilter.doFilter(ProxyFilter.java:56)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.extremecomponents.table.filter.AbstractExportFilter.doFilter(AbstractExportFilter.java:49)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.opennms.web.servlet.StoreRequestPropertiesFilter.doFilter(StoreRequestPropertiesFilter.java:79)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.opennms.web.springframework.security.AuthFilterEnabler.doFilter(AuthFilterEnabler.java:108)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:343)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:260)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.springframework.orm.hibernate3.support.OpenSessionInViewFilter.doFilterInternal(OpenSessionInViewFilter.java:232)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:106)
at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1288)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:443)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:137)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:556)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:227)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1044)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:372)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:189)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:978)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:135)
at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:255)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:154)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:116)
at org.eclipse.jetty.server.Server.handle(Server.java:365)
at org.eclipse.jetty.server.AbstractHttpConnection.handleRequest(AbstractHttpConnection.java:486)
at org.eclipse.jetty.server.AbstractHttpConnection.headerComplete(AbstractHttpConnection.java:933)
at org.eclipse.jetty.server.AbstractHttpConnection$RequestHandler.headerComplete(AbstractHttpConnection.java:995)
at org.eclipse.jetty.http.HttpParser.parseNext(HttpParser.java:644)
at org.eclipse.jetty.http.HttpParser.parseAvailable(HttpParser.java:235)
at org.eclipse.jetty.server.AsyncHttpConnection.handle(AsyncHttpConnection.java:82)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint.handle(SelectChannelEndPoint.java:667)
at org.eclipse.jetty.io.nio.SelectChannelEndPoint$1.run(SelectChannelEndPoint.java:52)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:608)
at org.eclipse.jetty.util.thread.QueuedThreadPool$3.run(QueuedThreadPool.java:543)
at java.lang.Thread.run(Thread.java:745)

It looks like it's part of the custom configuration format used for NRTG.