Null Properties Omitting Value Tag

[southernprogrammer]

Consider the XML at the bottom of this ticket.

Notice that the following tags do not have a "value" property.

<log4j:data name="ContentType"/>
<log4j:data name="ContentLength"/>

The log viewer that I use is OtrosLogViewer and it cannot parse this data. In fact, it causes no logs to be seen at all because of the parsing error. Currently I'm filtering all null properties with the formatter option UsePropertyFilter to keep this issue from occurring.

I'm okay with this being something that I override with configuration, as not all parsers might not have this issue.

Maybe something like configureOptions.SetNullPropertyValue(NullPropertyValue.NULL) and have the NullPropertyValue enum have the following options: NULL, EMPTY, OMIT. We could also allow for any string to be used.

I will note that < and > must be replaced with < and > in the value

<log4j:event logger="Microsoft.AspNetCore.Hosting.Diagnostics" timestamp="1745594909923" level="INFO" thread="9">
	<log4j:properties>
		<log4j:data name="Protocol" value="HTTP/1.1"/>
		<log4j:data name="Method" value="OPTIONS"/>
		<log4j:data name="ContentType"/>
		<log4j:data name="ContentLength"/>
		<log4j:data name="Scheme" value="https"/>
		<log4j:data name="Host" value="testdev.3-gis.com"/>
		<log4j:data name="PathBase" value="/3GISISP/API"/>
		<log4j:data name="Path" value="/Authenticate"/>
		<log4j:data name="QueryString" value=""/>
		<log4j:data name="EventId.Id" value="1"/>
		<log4j:data name="SpanId" value="c098ff8ab33d0cce"/>
		<log4j:data name="TraceId" value="218c5892763aa30255de1a6fcd356041"/>
		<log4j:data name="ParentId" value="0000000000000000"/>
		<log4j:data name="RequestId" value="40001124-0001-f900-b63f-84710c7967bb"/>
		<log4j:data name="RequestPath" value="/3GISISP/API/Authenticate"/>
		<log4j:data name="log4japp" value="ISPServer.dll(15800)"/>
		<log4j:data name="log4jmachinename" value="TESTDEV"/>
	</log4j:properties>
	<log4j:message>Request starting HTTP/1.1 OPTIONS https://testdev.3-gis.com/3GISISP/API/Authenticate - null null</log4j:message>
</log4j:event>

[0xced]

That's a very good point! The current implementation is incorrect. The null text can be controlled by the static SystemInfo.NullText property in log4net. It defaults to (null) and the value attribute should be always written.

I will add a new configuration option for null text in the next release.