[JS IR] Fix klib fingerprint format

^KT-56961 Fixed

compiler/ir/serialization.js/src/org/jetbrains/kotlin/ir/backend/js/FileFingerprints.kt

@@ -57,6 +57,10 @@ value class SerializedIrFileFingerprint private constructor(val fileFingerprint:
     constructor(file: SerializedIrFile) : this(calculateFileFingerprint(file))
 
     constructor(lib: KotlinLibrary, fileIndex: Int) : this(calculateFileFingerprint(lib, fileIndex))
+
+    override fun toString(): String {
+        return fileFingerprint.toString()
+    }
 }
 
 @JvmInline
@@ -96,6 +100,10 @@ value class SerializedKlibFingerprint(val klibFingerprint: FingerprintHash) {
     constructor(fileFingerprints: List<SerializedIrFileFingerprint>) : this(fileFingerprints.calculateKlibFingerprint())
 
     constructor(klibFile: File) : this(FingerprintHash(klibFile.calculateKlibHash()))
+
+    override fun toString(): String {
+        return klibFingerprint.toString()
+    }
 }
 
 private const val FILE_FINGERPRINTS_SEPARATOR = " "

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/Kotlin2JsGradlePluginIT.kt

@@ -412,6 +412,36 @@ class Kotlin2JsIrGradlePluginIT : AbstractKotlin2JsGradlePluginIT(true) {
             build("compileDevelopmentExecutableKotlinJs")
         }
     }
+
+    @DisplayName("klib fingerprints")
+    @GradleTest
+    fun testKlibFingerprints(gradleVersion: GradleVersion) {
+        project("kotlin2JsIrICProject", gradleVersion) {
+            val fingerprints = Array(2) {
+                build("compileDevelopmentExecutableKotlinJs")
+
+                val manifestLines = projectPath.resolve("build/classes/kotlin/main/default/manifest").readLines()
+                val serializedKlibFingerprint = manifestLines.singleOrNull { it.startsWith("serializedKlibFingerprint=") }
+                assertNotNull(serializedKlibFingerprint) { "can not find serializedKlibFingerprint" }
+                assertTrue("bad serializedKlibFingerprint format '$serializedKlibFingerprint'") {
+                    Regex("serializedKlibFingerprint=[a-z0-9]+\\.[a-z0-9]+").matches(serializedKlibFingerprint)
+                }
+
+                val serializedIrFileFingerprints = manifestLines.singleOrNull { it.startsWith("serializedIrFileFingerprints=") }
+                assertNotNull(serializedIrFileFingerprints) { "can not find serializedIrFileFingerprints" }
+                assertTrue("bad serializedIrFileFingerprints format '$serializedIrFileFingerprints'") {
+                    // kotlin2JsIrICProject has 2 files
+                    Regex("serializedIrFileFingerprints=[a-z0-9]+\\.[a-z0-9]+ [a-z0-9]+\\.[a-z0-9]+").matches(serializedIrFileFingerprints)
+                }
+
+                build("clean")
+
+                serializedKlibFingerprint to serializedIrFileFingerprints
+            }
+
+            assertEquals(fingerprints[0], fingerprints[1], "fingerprints must be stable")
+        }
+    }
 }
 
 @JsGradlePluginTests