implement ephemeral addons for platform version comparison

common/implementation/base/src/main/java/com/dfsek/terra/AbstractPlatform.java

@@ -18,6 +18,10 @@
 package com.dfsek.terra;
 
 import com.dfsek.tectonic.loading.TypeRegistry;
+
+import com.dfsek.terra.addon.EphemeralAddon;
+import com.dfsek.terra.addon.InternalAddon;
+
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.io.IOUtils;
 import org.slf4j.Logger;
@@ -33,9 +37,9 @@ import java.io.UncheckedIOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Path;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 
 import com.dfsek.terra.addon.BootstrapAddonLoader;
 import com.dfsek.terra.addon.DependencySorter;
@@ -102,8 +106,8 @@ public abstract class AbstractPlatform implements Platform {
         return manager;
     }
     
-    protected Optional<BaseAddon> platformAddon() {
-        return Optional.empty();
+    protected Iterable<BaseAddon> platformAddon() {
+        return Collections.emptySet();
     }
     
     protected void load() {
@@ -175,7 +179,7 @@ public abstract class AbstractPlatform implements Platform {
         
         addonList.add(internalAddon);
         
-        platformAddon().ifPresent(addonList::add);
+        platformAddon().forEach(addonList::add);
         
         BootstrapAddonLoader bootstrapAddonLoader = new BootstrapAddonLoader();
         
@@ -214,7 +218,9 @@ public abstract class AbstractPlatform implements Platform {
         sorter.sort().forEach(addon -> {
             platformInjector.inject(addon);
             addon.initialize();
-            addonRegistry.register(addon.getID(), addon);
+            if(!(addon instanceof EphemeralAddon)) { // ephemeral addons exist only for version checking
+                addonRegistry.register(addon.getID(), addon);
+            }
         });
     
         eventManager.getHandler(FunctionalEventHandler.class)

common/implementation/base/src/main/java/com/dfsek/terra/addon/EphemeralAddon.java

@@ -0,0 +1,26 @@
+package com.dfsek.terra.addon;
+
+import ca.solostudios.strata.version.Version;
+
+import com.dfsek.terra.api.addon.BaseAddon;
+
+
+public class EphemeralAddon implements BaseAddon {
+    private final Version version;
+    private final String id;
+    
+    public EphemeralAddon(Version version, String id) {
+        this.version = version;
+        this.id = id;
+    }
+    
+    @Override
+    public Version getVersion() {
+        return version;
+    }
+    
+    @Override
+    public String getID() {
+        return id;
+    }
+}

common/implementation/base/src/main/java/com/dfsek/terra/addon/InternalAddon.java

@@ -15,7 +15,7 @@
  * along with Terra.  If not, see <https://www.gnu.org/licenses/>.
  */
 
-package com.dfsek.terra;
+package com.dfsek.terra.addon;
 
 import ca.solostudios.strata.Versions;
 import ca.solostudios.strata.version.Version;