Support downloading additional artifacts (sources, javadoc, etc.)

model/src/main/kotlin/org/nixos/gradle2nix/model/ArtifactType.kt

@@ -0,0 +1,9 @@
+package org.nixos.gradle2nix.model
+
+enum class ArtifactType {
+    DOXYGEN,
+    JAVADOC,
+    SAMPLES,
+    SOURCES,
+    USERMANUAL,
+}

model/src/main/kotlin/org/nixos/gradle2nix/model/PluginParameters.kt

@@ -2,3 +2,4 @@ package org.nixos.gradle2nix.model
 
 const val RESOLVE_PROJECT_TASK = "resolveProjectArtifacts"
 const val RESOLVE_ALL_TASK = "resolveAllArtifacts"
+const val ARTIFACTS_PROPERTY = "org.nixos.gradle2nix.artifacts"