From the MPP guide: "By default, a sources JAR is added to each publication in addition to its main artifact." Does this mean I don't need to include

from(components["java"])

and

artifact(tasks["sourcesJar"])

within my maven publication in my MPP build file?

Correct, so long as you add the generated maven publication it’ll include the sources jar

Do you happen to know what the generated publication names are? I can't seem to find it in the documentation and I need them for the signing plugin

The publication names match the target names. There is one publication per target that you define, plus, a publication named

metadata

for the built-in target of the same name, plus, if you publish a library with Gradle module metadata, there is a 'root' publication named

kotlinMultiplatform

(this one does not have a sources JAR). You can get the existing publications from the project through debug output from the build script, like:

println(publishing.publications.names)