Show JAR manifest diff details

```diff
OLD: old.jar
NEW: new.jar

 JAR   │ old        │ new        │ diff
───────┼────────────┼────────────┼──────
 class │  12.86 MiB │  12.86 MiB │  0 B
 other │ 375.23 KiB │ 375.22 KiB │ -8 B
───────┼────────────┼────────────┼──────
 total │  13.23 MiB │  13.23 MiB │ -8 B

 CLASSES │ old   │ new   │ diff
─────────┼───────┼───────┼───────────
 classes │  3308 │  3308 │ 0 (+0 -0)
 methods │ 37498 │ 37498 │ 0 (+0 -0)
  fields │ 15282 │ 15282 │ 0 (+0 -0)

=================
====   JAR   ====
=================

 size     │ diff │ path
──────────┼──────┼──────────────────────────────────────────────────
    960 B │ -4 B │ ∆ META-INF/MANIFEST.MF
    830 B │ -4 B │ ∆ META-INF/micrometer-registry-statsd.properties
──────────┼──────┼──────────────────────────────────────────────────
 1.75 KiB │ -8 B │ (total)

======================
====   MANIFEST   ====
======================

@@ -2,5 +2,5 @@
 Automatic-Module-Name: micrometer.registry.statsd
-Implementation-Title: io.micrometer#micrometer-registry-statsd;1.17.0-SN
- APSHOT
-Implementation-Version: 1.17.0-SNAPSHOT
+Implementation-Title: io.micrometer#micrometer-registry-statsd;0.1.0-SNA
+ PSHOT
+Implementation-Version: 0.1.0-SNAPSHOT
 Built-Status: integration
@@ -9,10 +9,10 @@
 Build-Timezone: Asia/Shanghai
-Build-Date-UTC: 2026-03-26T01:17:09.160902Z
-Build-Date: 2026-03-26_09:17:09
+Build-Date-UTC: 2026-03-26T01:44:09.621464Z
+Build-Date: 2026-03-26_09:44:09
 Gradle-Version: 9.4.1
 Module-Source:
-Module-Origin: https://github.com/micrometer-metrics/micrometer.git
-Change: 50362b5
-Full-Change: 50362b5e874e650ebbde888de300f5949e6720fd
-Branch: main
+Module-Origin: https://github.com/Goooler/micrometer.git
+Change: 0d10057
+Full-Change: 0d100579e6285843e49b398f974cddd06bd843b0
+Branch: shadow-config
 Build-Host: Gooolers-MacBook-Pro.local
```

Author: Goooler

CHANGELOG.md

@@ -6,6 +6,7 @@
 **Added**
 - Add `--summary-only` flag.
 - Support diffing bytecode versions for classes.
+- Show JAR manifest diff details.
 
 **Changed**
 - Replace `com.jakewharton.diffuse.io.Size` with `me.saket.bytesize.ByteSize` in the APIs.

formats/api/formats.api

@@ -280,11 +280,12 @@ public final class com/jakewharton/diffuse/format/Field : com/jakewharton/diffus
 
 public final class com/jakewharton/diffuse/format/Jar : com/jakewharton/diffuse/format/BinaryFormat, com/jakewharton/diffuse/format/CodeBinary {
 	public static final field Companion Lcom/jakewharton/diffuse/format/Jar$Companion;
-	public synthetic fun <init> (Ljava/lang/String;Lcom/jakewharton/diffuse/format/ArchiveFiles;Ljava/util/List;Ljava/util/List;Ljava/util/List;Lkotlin/jvm/internal/DefaultConstructorMarker;)V
+	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/String;Lcom/jakewharton/diffuse/format/ArchiveFiles;Ljava/util/List;Ljava/util/List;Ljava/util/List;Lkotlin/jvm/internal/DefaultConstructorMarker;)V
 	public final fun getClasses ()Ljava/util/List;
 	public fun getDeclaredMembers ()Ljava/util/List;
 	public fun getFilename ()Ljava/lang/String;
 	public final fun getFiles ()Lcom/jakewharton/diffuse/format/ArchiveFiles;
+	public final fun getManifest ()Ljava/lang/String;
 	public fun getMembers ()Ljava/util/List;
 	public fun getReferencedMembers ()Ljava/util/List;
 	public static final fun parse (Lcom/jakewharton/diffuse/io/Input;)Lcom/jakewharton/diffuse/format/Jar;

formats/src/main/kotlin/com/jakewharton/diffuse/format/Jar.kt

@@ -8,6 +8,7 @@ import com.jakewharton.diffuse.io.Input
 class Jar
 private constructor(
   override val filename: String?,
+  val manifest: String,
   val files: ArchiveFiles,
   val classes: List<Class>,
   override val declaredMembers: List<Member>,
@@ -16,6 +17,8 @@ private constructor(
   override val members = declaredMembers + referencedMembers
 
   companion object {
+    private const val MANIFEST_PATH = "META-INF/MANIFEST.MF"
+
     @JvmStatic
     @JvmName("parse")
     fun Input.toJar(): Jar {
@@ -30,7 +33,14 @@ private constructor(
         // Declared methods are likely to reference other declared members. Ensure all are removed.
         referencedMembers -= declaredMembers
 
-        return Jar(name, files, classes, declaredMembers.sorted(), referencedMembers.sorted())
+        return Jar(
+          filename = name,
+          manifest = zip[MANIFEST_PATH].asInput().toUtf8(),
+          files = files,
+          classes = classes,
+          declaredMembers = declaredMembers.sorted(),
+          referencedMembers = referencedMembers.sorted(),
+        )
       }
     }
   }

reports/src/main/kotlin/com/jakewharton/diffuse/diff/JarDiff.kt

@@ -13,8 +13,9 @@ internal class JarDiff(
 ) : BinaryDiff {
   val archive = ArchiveFilesDiff(oldJar.files, newJar.files, includeCompressed = false)
   val jars = JarsDiff(listOf(oldJar), oldMapping, listOf(newJar), newMapping)
+  val manifest = JarManifestDiff(oldJar.manifest, newJar.manifest)
 
-  val changed = jars.changed || archive.changed
+  val changed = jars.changed || archive.changed || manifest.changed
 
   override fun toTextReport(summaryOnly: Boolean): Report = JarDiffTextReport(this, summaryOnly)
 }

reports/src/main/kotlin/com/jakewharton/diffuse/diff/JarManifestDiff.kt

@@ -0,0 +1,32 @@
+package com.jakewharton.diffuse.diff
+
+import com.github.difflib.DiffUtils
+import com.github.difflib.UnifiedDiffUtils
+
+internal class JarManifestDiff(oldManifest: String, newManifest: String) {
+  val diff: List<String> =
+    if (oldManifest == newManifest) {
+      emptyList()
+    } else {
+      val oldLines = oldManifest.lines()
+      val newLines = newManifest.lines()
+      val diff = DiffUtils.diff(oldLines, newLines)
+      UnifiedDiffUtils.generateUnifiedDiff(MANIFEST_PATH, MANIFEST_PATH, oldLines, diff, 1)
+    }
+
+  val changed = diff.isNotEmpty()
+
+  internal companion object {
+    const val MANIFEST_PATH = "META-INF/MANIFEST.MF"
+  }
+}
+
+internal fun JarManifestDiff.toDetailReport() = buildString {
+  if (diff.isNotEmpty()) {
+    appendLine()
+    diff
+      .drop(2) // Skip file name headers.
+      .forEach(::appendLine)
+    appendLine()
+  }
+}

reports/src/main/kotlin/com/jakewharton/diffuse/report/text/JarDiffTextReport.kt

@@ -29,6 +29,13 @@ internal class JarDiffTextReport(private val jarDiff: JarDiff, private val summa
         appendLine("=================")
         appendLine(jarDiff.archive.toDetailReport())
       }
+      if (jarDiff.manifest.changed) {
+        appendLine()
+        appendLine("======================")
+        appendLine("====   MANIFEST   ====")
+        appendLine("======================")
+        appendLine(jarDiff.manifest.toDetailReport())
+      }
       if (jarDiff.jars.changed) {
         appendLine()
         appendLine("=====================")

reports/src/test/kotlin/com/jakewharton/diffuse/JarDiffTextReportTest.kt

@@ -0,0 +1,63 @@
+package com.jakewharton.diffuse
+
+import assertk.assertThat
+import assertk.assertions.contains
+import assertk.assertions.doesNotContain
+import com.jakewharton.diffuse.diff.JarDiff
+import com.jakewharton.diffuse.diff.JarManifestDiff.Companion.MANIFEST_PATH
+import com.jakewharton.diffuse.format.ApiMapping
+import com.jakewharton.diffuse.format.Jar
+import com.jakewharton.diffuse.format.Jar.Companion.toJar
+import com.jakewharton.diffuse.io.Input.Companion.asInput
+import java.io.ByteArrayOutputStream
+import java.util.jar.JarOutputStream
+import java.util.zip.ZipEntry
+import okio.ByteString.Companion.toByteString
+import org.junit.Test
+
+class JarDiffTextReportTest {
+  @Test
+  fun manifestChanged() {
+    val oldJar = jar("old.jar", "Manifest-Version: 1.0\nCreated-By: old")
+    val newJar = jar("new.jar", "Manifest-Version: 1.0\nCreated-By: new")
+
+    val report =
+      JarDiff(oldJar, ApiMapping.EMPTY, newJar, ApiMapping.EMPTY).toTextReport(false).toString()
+
+    assertThat(report)
+      .contains(
+        """
+        |======================
+        |====   MANIFEST   ====
+        |======================
+        |
+        |@@ -1,2 +1,2 @@
+        | Manifest-Version: 1.0
+        |-Created-By: old
+        |+Created-By: new
+        """
+          .trimMargin()
+      )
+  }
+
+  @Test
+  fun manifestNotChanged() {
+    val oldJar = jar("old.jar", "Manifest-Version: 1.0\nCreated-By: same")
+    val newJar = jar("new.jar", "Manifest-Version: 1.0\nCreated-By: same")
+
+    val report =
+      JarDiff(oldJar, ApiMapping.EMPTY, newJar, ApiMapping.EMPTY).toTextReport(false).toString()
+
+    assertThat(report).doesNotContain("====   MANIFEST   ====")
+  }
+
+  private fun jar(name: String, manifestContent: String): Jar {
+    val bytes = ByteArrayOutputStream()
+    JarOutputStream(bytes).use { jar ->
+      jar.putNextEntry(ZipEntry(MANIFEST_PATH))
+      jar.write(manifestContent.toByteArray())
+      jar.closeEntry()
+    }
+    return bytes.toByteArray().toByteString().asInput(name).toJar()
+  }
+}