refactor: port TEdgePart to Java

Replaces TEdgePart.scala with a Java interface and retains the
TEdgePart$class bridge for OpenComputers. The interface is
descriptor-identical to the reference, the bridge adds only a private
constructor, and the emitted class-file set for this area is unchanged.

TMultiPart does not declare conductsRedstone and neither does anything in
the microblock superclass chain, so it becomes a real default method and
no in-repo Scala needed changing. The generated microblock classes now
resolve the interface default instead of a Scala trait forwarder, which
the functional generation case added during the TFacePart port covers.

conductsRedstone is kept on the bridge even though OpenComputers only
links against $init$, since the bridge class is being kept regardless.

Validated with 61 plain-JVM tests, a clean build, and the Java 8 Forge
dedicated-server suite.

JAVA_MIGRATION_DIVERGENCES.md

@@ -411,3 +411,35 @@ private static method rather than a closure class in both versions.
 - Clean `spotlessApply checkstyleTest build`: passing.
 - Java 8 Forge dedicated-server suite: 3 tests, 0 failures, 0 errors.
 - Real placement into a world needs a client or a server scenario and stays on the functional and manual layers.
+
+## 2026-08-14 — TEdgePart Java port
+
+### Observable behavior
+
+No known divergence. `conductsRedstone` still returns false and `TEdgePart` still extends `TSlottedPart`.
+
+### Default method, same test as TFacePart
+
+`TMultiPart` does not declare `conductsRedstone`, and nothing in the microblock superclass chain does either, so the
+member is emitted as a real Java `default`. `EdgeMicroblock` never declared its own forwarder even in the reference,
+because it is a Scala trait rather than a concrete class, and the generated concrete classes now resolve the interface
+default instead of a Scala trait forwarder. The functional microblock generation case added during the `TFacePart`
+port already covers that resolution path.
+
+No in-repo Scala needed changing.
+
+### Supported JVM API
+
+- `TEdgePart` is descriptor-identical to the reference.
+- `TEdgePart$class` keeps both statics and adds only a private constructor. OpenComputers links against `$init$` only,
+  but `conductsRedstone` is retained because the bridge class is being kept regardless and dropping one static from a
+  live bridge would be a gratuitous shape change.
+- The emitted class-file set for this area is unchanged; the Scala implementation generated no closure classes here.
+
+### Validation
+
+- `EdgePartCharacterizationTest`: 3 tests, 0 failures, 0 errors, unchanged from the Scala baseline.
+- `TEdgePartBinaryCompatibilityTest`: 1 test, 0 failures, 0 errors.
+- Complete plain-JVM suite: 61 tests, 0 failures, 0 errors.
+- Clean `spotlessApply checkstyleTest build`: passing.
+- Java 8 Forge dedicated-server suite: 3 tests, 0 failures, 0 errors.

src/main/scala/codechicken/multipart/TEdgePart$class.java

@@ -0,0 +1,17 @@
+package codechicken.multipart;
+
+/**
+ * Binary bridge for Scala implementations compiled against the original trait. Their forwarders call these statics
+ * directly, so the body cannot delegate back to the instance method without recursing.
+ */
+@Deprecated
+public abstract class TEdgePart$class {
+
+    private TEdgePart$class() {}
+
+    public static boolean conductsRedstone(TEdgePart part) {
+        return false;
+    }
+
+    public static void $init$(TEdgePart part) {}
+}

src/main/scala/codechicken/multipart/TEdgePart.java

@@ -0,0 +1,14 @@
+package codechicken.multipart;
+
+/**
+ * Interface which must be implemented by parts that go in an edge slot.
+ * <p>
+ * TMultiPart does not declare conductsRedstone, so it can safely be a default method.
+ */
+public interface TEdgePart extends TSlottedPart {
+
+    /** Return true if this part can conduct redstone signal or let redstone signal pass through it. */
+    default boolean conductsRedstone() {
+        return false;
+    }
+}

src/main/scala/codechicken/multipart/TEdgePart.scala

@@ -1,11 +0,0 @@
-package codechicken.multipart
-
-/** Interface which must be implemented by parts that go in an edge slot.
-  */
-trait TEdgePart extends TSlottedPart {
-
-  /** Return true if this part can conduct redstone signal or let redstone
-    * signal pass through it.
-    */
-  def conductsRedstone = false
-}