Fix builder.State.write internalization

Using generic Map interface instead of SimpleLookupTable showed up that
State.write(DataOutputStream) did use Arrays (char[] / char[][]) as key
in internedRootNames, internedQualifiedNames, internedSimpleNames.

Arrays however do have equals() contract based on identity. Therefore
the code did not deduplicate anything as intended.
It normally only did not matter as most char arrays in jdt are already
weakly deduplicated.

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/util/CharArray.java

@@ -22,15 +22,11 @@
  * <code>Arrays.hashCode</code> and <code>Arrays.equals</code>.
  * </p>
  */
-final class CharArray implements Comparable<CharArray> {
-	private final char[] key;
-
-	public CharArray(char[] key) {
-		this.key = key;
-	}
+public final record CharArray(char[] key) implements Comparable<CharArray> {
 
 	@Override
 	public int compareTo(CharArray o) {
+		// just any technical sort order for Comparable interface used in HashMap https://openjdk.org/jeps/180
 		return Arrays.compare(this.key, o.key);
 	}
 
@@ -40,24 +36,17 @@ public char[] getKey() {
 
 	@Override
 	public boolean equals(Object obj) {
-		if (this == obj) {
-			return true;
-		}
-		if (!(obj instanceof CharArray)) {
-			return false;
+		if (obj instanceof CharArray other) {
+			return Arrays.equals(this.key, other.key);
 		}
-		CharArray other = (CharArray) obj;
-		return Arrays.equals(this.key, other.key);
+		return false;
 	}
 
 	@Override
 	public int hashCode() {
 		return Arrays.hashCode(this.key);
 	}
 
-	/**
-	 * @return <code>Arrays.toString</code> of the underlying array
-	 */
 	@Override
 	public String toString() {
 		return Arrays.toString(this.key);

org.eclipse.jdt.core.compiler.batch/src/org/eclipse/jdt/internal/compiler/util/CharCharArray.java

@@ -0,0 +1,61 @@
+/*******************************************************************************
+ * Copyright (c) 2025 jkubitz and others.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     jkubitz - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.jdt.internal.compiler.util;
+
+import java.util.Arrays;
+
+/**
+ * Wrapper around char[][] that can be used as a key in a Map or Set.
+ */
+public final record CharCharArray(char[][] key) implements Comparable<CharCharArray> {
+
+	@Override
+	public int compareTo(CharCharArray other) {
+		// just any technical sort order for Comparable interface used in HashMap https://openjdk.org/jeps/180
+		int d = this.key.length - other.key.length;
+		if (d != 0) {
+			return d;
+		}
+		int length = this.key.length;
+		for (int i = 0; i < length; i++) {
+			int c = Arrays.compare(this.key[i], other.key[i]);
+			if (c != 0) {
+				return c;
+			}
+		}
+		return 0;
+	}
+
+	public char[][] getKey() {
+		return this.key;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (obj instanceof CharCharArray other) {
+			return Arrays.deepEquals(this.key, other.key);
+		}
+		return false;
+	}
+
+	@Override
+	public int hashCode() {
+		return Arrays.deepHashCode(this.key);
+	}
+
+	@Override
+	public String toString() {
+		return Arrays.deepToString(this.key);
+	}
+}