From 5a8181c9151c863a293acb60165d26dfe349add6 Mon Sep 17 00:00:00 2001
From: Nicklas Lundin <nicklasl@spotify.com>
Date: Wed, 5 Jul 2023 21:58:32 +0200
Subject: [PATCH] Format ISO8601 dates with milliseconds.

Serializes Date objects (backing of Value.Instant) as ISO8601 WITH milliseconds. Also adds fallback parsing support where milliseconds are not passed.
---
 .../main/java/dev/openfeature/sdk/Value.kt    | 22 +++++++++++++------
 .../java/dev/openfeature/sdk/ValueTests.kt    | 10 ++++++---
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/OpenFeature/src/main/java/dev/openfeature/sdk/Value.kt b/OpenFeature/src/main/java/dev/openfeature/sdk/Value.kt
index ad25cb6..20fa25c 100644
--- a/OpenFeature/src/main/java/dev/openfeature/sdk/Value.kt
+++ b/OpenFeature/src/main/java/dev/openfeature/sdk/Value.kt
@@ -53,6 +53,7 @@ sealed interface Value {
         override fun equals(other: Any?): kotlin.Boolean {
             return other is Null
         }
+
         override fun hashCode(): Int {
             return javaClass.hashCode()
         }
@@ -73,14 +74,21 @@ object ValueSerializer : JsonContentPolymorphicSerializer<Value>(Value::class) {
     }
 }
 
+@SuppressLint("SimpleDateFormat")
 object DateSerializer : KSerializer<Date> {
-    @SuppressLint("SimpleDateFormat")
-    private val df = SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'").apply { timeZone = TimeZone.getTimeZone("UTC") }
+    private val dateFormatter =
+        SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSS'Z'").apply { timeZone = TimeZone.getTimeZone("UTC") }
+    private val fallbackDateFormatter =
+        SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'").apply { timeZone = TimeZone.getTimeZone("UTC") }
     override val descriptor = PrimitiveSerialDescriptor("Instant", PrimitiveKind.STRING)
-    override fun serialize(encoder: Encoder, value: Date) = encoder.encodeString(df.format(value))
-    override fun deserialize(decoder: Decoder): Date = try {
-        df.parse(decoder.decodeString()) ?: throw IllegalArgumentException("unable to parse ${decoder.decodeString()}")
-    } catch (e: Exception) {
-        throw IllegalArgumentException(e)
+    override fun serialize(encoder: Encoder, value: Date) = encoder.encodeString(dateFormatter.format(value))
+    override fun deserialize(decoder: Decoder): Date = with(decoder.decodeString()) {
+        try {
+            dateFormatter.parse(this)
+                ?: throw IllegalArgumentException("unable to parse $this")
+        } catch (e: Exception) {
+            fallbackDateFormatter.parse(this)
+                ?: throw IllegalArgumentException("unable to parse $this")
+        }
     }
 }
\ No newline at end of file
diff --git a/OpenFeature/src/test/java/dev/openfeature/sdk/ValueTests.kt b/OpenFeature/src/test/java/dev/openfeature/sdk/ValueTests.kt
index 91e8d62..e71727e 100644
--- a/OpenFeature/src/test/java/dev/openfeature/sdk/ValueTests.kt
+++ b/OpenFeature/src/test/java/dev/openfeature/sdk/ValueTests.kt
@@ -48,8 +48,12 @@ class ValueTests {
 
     @Test
     fun testStructShouldConvertToStruct() {
-        val value = Value.Structure(mapOf("field1" to Value.Integer(3), "field2" to Value.String("test")))
-        Assert.assertEquals(value.asStructure(), mapOf("field1" to Value.Integer(3), "field2" to Value.String("test")))
+        val value =
+            Value.Structure(mapOf("field1" to Value.Integer(3), "field2" to Value.String("test")))
+        Assert.assertEquals(
+            value.asStructure(),
+            mapOf("field1" to Value.Integer(3), "field2" to Value.String("test"))
+        )
     }
 
     @Test
@@ -82,7 +86,7 @@ class ValueTests {
 
     @Test
     fun testJsonDecode() {
-        val stringInstant = "2023-03-01T14:01:46Z"
+        val stringInstant = "2023-03-01T14:01:46.321Z"
         val json = "{" +
             "  \"structure\": {" +
             "    \"null\": {}," +