Remove most generics in services and candidates

They actually create more problems than they solve resulting in a bunch of unsafe casts

src/main/java/org/spongepowered/plugin/PluginCandidate.java

@@ -29,9 +29,8 @@
 /**
  * Represents the combination of a {@link PluginMetadata metadata} and {@link PluginResource resource}
  * that will be a candidate for a {@link PluginContainer container}.
- * @param <P> The resource type
  */
-public interface PluginCandidate<P extends PluginResource> {
+public interface PluginCandidate {
 
     /**
      * @return The {@link PluginMetadata metadata}
@@ -41,5 +40,5 @@ public interface PluginCandidate<P extends PluginResource> {
     /**
      * @return The {@link PluginResource resource}
      */
-    P resource();
+    PluginResource resource();
 }

src/main/java/org/spongepowered/plugin/PluginLanguageService.java

@@ -33,9 +33,8 @@
  * No class loading should occur at this time
  * <p>
  * Implementors are required to have a no-args constructor
- * @param <P> The resource type
  */
-public interface PluginLanguageService<P extends PluginResource> {
+public interface PluginLanguageService {
 
     /**
      * @return The {@link String name}
@@ -65,5 +64,5 @@ public interface PluginLanguageService<P extends PluginResource> {
      * @param resource The resource
      * @return The {@link List candidates}
      */
-    List<PluginCandidate<P>> createPluginCandidates(Environment environment, P resource) throws Exception;
+    List<PluginCandidate> createPluginCandidates(Environment environment, PluginResource resource) throws Exception;
 }

src/main/java/org/spongepowered/plugin/PluginLoader.java

@@ -30,10 +30,9 @@
  * A loader used to create and load {@link PluginContainer plugins}.
  * <p>
  * Implementors of this class are required to have a no-args constructor
- * @param <R> The resource type
  * @param <P> The container type
  */
-public interface PluginLoader<R extends PluginResource, P extends PluginContainer> {
+public interface PluginLoader<P extends PluginContainer> {
 
     /**
      * @return The {@link ArtifactVersion version}, as a maven artifact
@@ -49,5 +48,5 @@ public interface PluginLoader<R extends PluginResource, P extends PluginContaine
      * @param targetClassLoader The classloader
      * @throws InvalidPluginException If the candidate is invalid
      */
-    P loadPlugin(Environment environment, PluginCandidate<R> candidate, ClassLoader targetClassLoader) throws InvalidPluginException;
+    P loadPlugin(Environment environment, PluginCandidate candidate, ClassLoader targetClassLoader) throws InvalidPluginException;
 }

src/main/java/org/spongepowered/plugin/builtin/StandardPluginCandidate.java

@@ -28,33 +28,5 @@
 import org.spongepowered.plugin.PluginResource;
 import org.spongepowered.plugin.metadata.PluginMetadata;
 
-import java.util.StringJoiner;
-
-public final class StandardPluginCandidate<P extends PluginResource> implements PluginCandidate<P> {
-
-    private final PluginMetadata metadata;
-    private final P resource;
-
-    public StandardPluginCandidate(final PluginMetadata metadata, final P resource) {
-        this.metadata = metadata;
-        this.resource = resource;
-    }
-
-    @Override
-    public PluginMetadata metadata() {
-        return this.metadata;
-    }
-
-    @Override
-    public P resource() {
-        return this.resource;
-    }
-
-    @Override
-    public String toString() {
-        return new StringJoiner(", ", StandardPluginCandidate.class.getSimpleName() + "[", "]")
-                .add("metadata=" + this.metadata)
-                .add("resource=" + this.resource)
-                .toString();
-    }
+public record StandardPluginCandidate(PluginMetadata metadata, PluginResource resource) implements PluginCandidate {
 }

src/main/java/org/spongepowered/plugin/builtin/StandardPluginContainer.java

@@ -28,7 +28,6 @@
 import org.apache.logging.log4j.Logger;
 import org.spongepowered.plugin.PluginCandidate;
 import org.spongepowered.plugin.PluginContainer;
-import org.spongepowered.plugin.PluginResource;
 import org.spongepowered.plugin.metadata.PluginMetadata;
 
 import java.net.URI;
@@ -38,15 +37,15 @@
 
 public class StandardPluginContainer implements PluginContainer {
 
-    private final PluginCandidate<? extends PluginResource> candidate;
+    private final PluginCandidate candidate;
     private final Logger logger;
     private Object instance;
 
-    public StandardPluginContainer(final PluginCandidate<? extends PluginResource> candidate) {
+    public StandardPluginContainer(final PluginCandidate candidate) {
         this(Objects.requireNonNull(candidate, "candidate"), LogManager.getLogger(candidate.metadata().id()));
     }
 
-    public StandardPluginContainer(final PluginCandidate<? extends PluginResource> candidate, final Logger logger) {
+    public StandardPluginContainer(final PluginCandidate candidate, final Logger logger) {
         this.candidate = Objects.requireNonNull(candidate, "candidate");
         this.logger = Objects.requireNonNull(logger, "logger");
     }

src/main/java/org/spongepowered/plugin/builtin/StandardPluginLanguageService.java

@@ -45,24 +45,24 @@
 import java.util.Objects;
 import java.util.Optional;
 
-public abstract class StandardPluginLanguageService implements PluginLanguageService<PluginResource> {
+public abstract class StandardPluginLanguageService implements PluginLanguageService {
     protected final Logger logger = LogManager.getLogger(this.name());
 
     @Override
     public void initialize(final Environment environment) {
     }
 
     @Override
-    public List<PluginCandidate<PluginResource>> createPluginCandidates(final Environment environment, final PluginResource resource) throws Exception {
+    public List<PluginCandidate> createPluginCandidates(final Environment environment, final PluginResource resource) throws Exception {
         Objects.requireNonNull(environment, "environment");
         Objects.requireNonNull(resource, "resource");
 
         final String metadataPath = environment.blackboard().get(Keys.METADATA_FILE_PATH);
 
-        final List<PluginCandidate<PluginResource>> candidates = new LinkedList<>();
+        final List<PluginCandidate> candidates = new LinkedList<>();
 
         final Optional<InputStream> optStream = resource.openResource(metadataPath);
-        if (!optStream.isPresent()) {
+        if (optStream.isEmpty()) {
             this.logger.debug("Container in path '{}' doesn't have a metadata file, skipping...", resource.path());
             return candidates;
         }
@@ -85,7 +85,7 @@ public List<PluginCandidate<PluginResource>> createPluginCandidates(final Enviro
                         continue;
                     }
                     containerHasMetadata = true;
-                    candidates.add(new StandardPluginCandidate<>(metadata, resource));
+                    candidates.add(new StandardPluginCandidate(metadata, resource));
                 }
 
                 if (!containerHasMetadata) {