Add mainCapabilityAttribute to disambiguate project dependencies with multiple capabilities when bundling library jars

paperweight-lib/src/main/kotlin/io/papermc/paperweight/tasks/CreateBundlerJar.kt

@@ -200,9 +200,14 @@ abstract class CreateBundlerJar : ZippedTask() {
             return when (val ident = id.componentIdentifier) {
                 is ModuleComponentIdentifier -> ModuleId.fromIdentifier(id)
                 is ProjectComponentIdentifier -> {
-                    val capability = variant.capabilities.first()
-                    val version = capability.version ?: throw PaperweightException("Unknown version for ${capability.group}:${capability.name}")
-                    ModuleId(capability.group, capability.name, version)
+                    val mainCap = variant.attributes.getAttribute(mainCapabilityAttribute)
+                    if (mainCap != null) {
+                        ModuleId.parse(mainCap)
+                    } else {
+                        val capability = variant.capabilities.first()
+                        val version = capability.version ?: throw PaperweightException("Unknown version for ${capability.group}:${capability.name}")
+                        ModuleId(capability.group, capability.name, version)
+                    }
                 }
                 else -> throw PaperweightException("Unknown artifact result type: ${ident::class.java.name}")
             }

paperweight-lib/src/main/kotlin/io/papermc/paperweight/util/utils.kt

@@ -53,6 +53,7 @@ import kotlin.io.path.*
 import org.cadixdev.lorenz.merge.MergeResult
 import org.gradle.api.Project
 import org.gradle.api.Task
+import org.gradle.api.attributes.Attribute
 import org.gradle.api.file.FileCollection
 import org.gradle.api.file.FileSystemLocation
 import org.gradle.api.file.ProjectLayout
@@ -416,3 +417,5 @@ fun modifyManifest(path: Path, create: Boolean = true, op: Manifest.() -> Unit)
         path.outputStream().buffered().use { mf.write(it) }
     }
 }
+
+val mainCapabilityAttribute: Attribute<String> = Attribute.of("io.papermc.paperweight.main-capability", String::class.java)