fix(domain): make BinaryContent immutable class and strengthen defensive copy tests

Author: bsayli

src/main/java/io/github/blueprintplatform/codegen/domain/port/out/artifact/BinaryContent.java

@@ -4,29 +4,31 @@
 
 import java.util.Arrays;
 
-public record BinaryContent(byte[] bytes) {
+@SuppressWarnings("java:S6206")
+public final class BinaryContent {
+
+  private final byte[] bytes;
 
   public BinaryContent(byte[] bytes) {
     requireBinaryContent(bytes);
     this.bytes = Arrays.copyOf(bytes, bytes.length);
   }
 
-  @Override
   public byte[] bytes() {
     return Arrays.copyOf(bytes, bytes.length);
   }
 
   @Override
   public boolean equals(Object o) {
-    return (this == o) || (o instanceof BinaryContent(byte[] other) && Arrays.equals(bytes, other));
+    return (this == o)
+        || (o instanceof BinaryContent other && Arrays.equals(this.bytes, other.bytes));
   }
 
   @Override
   public int hashCode() {
     return Arrays.hashCode(bytes);
   }
 
-  @SuppressWarnings("NullableProblems")
   @Override
   public String toString() {
     return "BinaryContent[size=" + bytes.length + "]";

src/test/java/io/github/blueprintplatform/codegen/domain/port/out/artifact/GeneratedResourceTest.java

@@ -43,6 +43,31 @@ void text_nullContent_shouldFailContentNotBlank() {
             dve -> assertThat(dve.getMessageKey()).isEqualTo("file.content.not.blank"));
   }
 
+  @Test
+  @DisplayName(
+      "BinaryContent should defensively copy, and equals/hashCode/toString should be stable")
+  void binaryContent_shouldBeImmutableAndValueBased() {
+    byte[] original = new byte[] {1, 2, 3};
+
+    BinaryContent c1 = new BinaryContent(original);
+
+    original[0] = 9;
+
+    assertThat(c1.bytes()).containsExactly(1, 2, 3);
+
+    byte[] view = c1.bytes();
+    view[1] = 8;
+
+    assertThat(c1.bytes()).containsExactly(1, 2, 3);
+
+    BinaryContent c2 = new BinaryContent(new byte[] {1, 2, 3});
+    BinaryContent c3 = new BinaryContent(new byte[] {1, 2, 4});
+
+    assertThat(c1).isEqualTo(c2).hasSameHashCodeAs(c2).isNotEqualTo(c3);
+
+    assertThat(c1.toString()).contains("BinaryContent").contains("size=3");
+  }
+
   @Test
   @DisplayName("Binary should defensively copy bytes in ctor and accessor")
   void binary_shouldDefensivelyCopyBytes() {
@@ -51,13 +76,9 @@ void binary_shouldDefensivelyCopyBytes() {
     GeneratedBinaryResource binary =
         new GeneratedBinaryResource(Path.of("bin.dat"), new BinaryContent(original));
 
-    // ctor defensive copy (BinaryContent ctor kopyalıyor olmalı)
     original[0] = 9;
-
     byte[] fromGetter = binary.bytes();
     assertThat(fromGetter).containsExactly(1, 2, 3);
-
-    // accessor defensive copy (BinaryContent.bytes() kopya dönmeli)
     fromGetter[1] = 8;
 
     byte[] fromGetterAgain = binary.bytes();