fix: duplicate key exception

lib/build.gradle

@@ -9,6 +9,7 @@
 import com.github.spotbugs.snom.Confidence
 import com.github.spotbugs.snom.Effort
 import com.github.spotbugs.snom.SpotBugsTask
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
 
 repositories {
     google()
@@ -17,6 +18,7 @@ repositories {
     maven { url = 'https://plugins.gradle.org/m2/' }
 }
 
+apply plugin: "kotlin-android"
 apply plugin: 'com.android.library'
 apply plugin: "com.github.spotbugs"
 apply plugin: "io.gitlab.arturbosch.detekt"
@@ -61,6 +63,12 @@ android {
         targetCompatibility JavaVersion.VERSION_17
     }
 
+    kotlin {
+        compilerOptions {
+            jvmTarget = JvmTarget.JVM_17
+        }
+    }
+
     publishing {
         singleVariant('release') {
             withSourcesJar()

lib/src/main/java/com/nextcloud/android/sso/api/AidlNetworkRequest.java

@@ -251,7 +251,7 @@ public static class PlainHeader implements Serializable {
         private String name;
         private String value;
 
-        PlainHeader(String name, String value) {
+        public PlainHeader(String name, String value) {
             this.name = name;
             this.value = value;
         }

lib/src/main/java/com/nextcloud/android/sso/helper/Retrofit2Helper.java

@@ -19,9 +19,10 @@
 
 import java.lang.reflect.Type;
 import java.util.Arrays;
-import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
 import java.util.Optional;
-import java.util.stream.Collectors;
+import java.util.Set;
 
 import okhttp3.Headers;
 import okhttp3.Protocol;
@@ -51,15 +52,8 @@ public Response<T> execute() {
                 try {
                     final var response = nextcloudAPI.performNetworkRequestV2(nextcloudRequest);
                     final T body = nextcloudAPI.convertStreamToTargetEntity(response.getBody(), resType);
-                    final var headerMap = Optional.ofNullable(response.getPlainHeaders())
-                        .map(headers -> headers
-                            .stream()
-                            .collect(Collectors.toMap(
-                                AidlNetworkRequest.PlainHeader::getName,
-                                AidlNetworkRequest.PlainHeader::getValue)))
-                        .orElse(Collections.emptyMap());
-
-                    return Response.success(body, Headers.of(headerMap));
+                    final var headers = buildHeaders(response.getPlainHeaders());
+                    return Response.success(body, headers);
 
                 } catch (NextcloudHttpRequestFailedException e) {
                     return convertExceptionToResponse(e.getStatusCode(), Optional.ofNullable(e.getCause()).orElse(e));
@@ -126,4 +120,35 @@ private Response<T> convertExceptionToResponse(int statusCode, @NonNull Throwabl
             }
         };
     }
+
+    /**
+     * This preserves all distinct header values without combining them.
+     *
+     * @param plainHeaders List of headers from the response
+     * @return Headers object
+     */
+    public static Headers buildHeaders(List<AidlNetworkRequest.PlainHeader> plainHeaders) {
+        if (plainHeaders == null || plainHeaders.isEmpty()) {
+            return new Headers.Builder().build();
+        }
+
+        final Headers.Builder builder = new Headers.Builder();
+        final Set<String> seen = new HashSet<>();
+
+        for (var header : plainHeaders) {
+            final String name = header.getName();
+            final String value = header.getValue();
+
+            // Create a unique key for name:value combination
+            final String key = name.toLowerCase() + ":" + value;
+
+            // Only add if we haven't seen this exact name:value combination before
+            if (!seen.contains(key)) {
+                builder.add(name, value);
+                seen.add(key);
+            }
+        }
+
+        return builder.build();
+    }
 }

lib/src/test/java/com/nextcloud/android/sso/helper/Retrofit2HelperTest.kt

@@ -0,0 +1,241 @@
+/*
+ * Nextcloud Android SingleSignOn Library
+ *
+ * SPDX-FileCopyrightText: 2017-2025 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-FileCopyrightText: 2025 Alper Ozturk <[email protected]>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+package com.nextcloud.android.sso.helper
+
+import com.nextcloud.android.sso.api.AidlNetworkRequest
+import com.nextcloud.android.sso.helper.Retrofit2Helper.buildHeaders
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+@Suppress("MagicNumber", "TooManyFunctions")
+class Retrofit2HelperTest {
+
+    @Test
+    fun testBuildHeadersWhenGivenNullHeadersShouldReturnEmptyHeaders() {
+        val headers = buildHeaders(null)
+        assertEquals(0, headers.size)
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenEmptyHeadersListShouldReturnEmptyHeaders() {
+        val headers = buildHeaders(emptyList())
+        assertEquals(0, headers.size)
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenSingleHeaderShouldReturnThatHeader() {
+        val plainHeaders = listOf(
+            createPlainHeader("Content-Type", "application/json")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(1, headers.size)
+        assertEquals("application/json", headers["Content-Type"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenDuplicateHeadersShouldRemoveDuplicates() {
+        val plainHeaders = listOf(
+            createPlainHeader("X-Robots-Tag", "noindex, nofollow"),
+            createPlainHeader("X-Robots-Tag", "noindex, nofollow"),
+            createPlainHeader("X-Robots-Tag", "noindex, nofollow")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(1, headers.size)
+        assertEquals("noindex, nofollow", headers["X-Robots-Tag"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenMultipleDistinctValuesShouldKeepAllValues() {
+        val plainHeaders = listOf(
+            createPlainHeader("Set-Cookie", "session=abc123"),
+            createPlainHeader("Set-Cookie", "token=xyz789"),
+            createPlainHeader("Set-Cookie", "user=john")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(3, headers.size)
+        val cookies = headers.values("Set-Cookie")
+        assertEquals(3, cookies.size)
+        assertTrue(cookies.contains("session=abc123"))
+        assertTrue(cookies.contains("token=xyz789"))
+        assertTrue(cookies.contains("user=john"))
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenMixedDuplicateAndDistinctValuesShouldHandleCorrectly() {
+        val plainHeaders = listOf(
+            createPlainHeader("Set-Cookie", "session=abc"),
+            createPlainHeader("Set-Cookie", "session=abc"),
+            createPlainHeader("Set-Cookie", "token=xyz"),
+            createPlainHeader("X-Robots-Tag", "noindex"),
+            createPlainHeader("X-Robots-Tag", "noindex")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(3, headers.size)
+
+        val cookies = headers.values("Set-Cookie")
+        assertEquals(2, cookies.size)
+        assertTrue(cookies.contains("session=abc"))
+        assertTrue(cookies.contains("token=xyz"))
+
+        assertEquals("noindex", headers["X-Robots-Tag"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenCaseInsensitiveHeaderNamesShouldTreatAsSame() {
+        val plainHeaders = listOf(
+            createPlainHeader("Content-Type", "application/json"),
+            createPlainHeader("content-type", "application/json"),
+            createPlainHeader("CONTENT-TYPE", "application/json")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(1, headers.size)
+        assertEquals("application/json", headers["Content-Type"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenCaseInsensitiveHeaderNamesWithDifferentValuesShouldKeepAll() {
+        val plainHeaders = listOf(
+            createPlainHeader("Content-Type", "application/json"),
+            createPlainHeader("content-type", "text/html"),
+            createPlainHeader("CONTENT-TYPE", "application/xml")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(3, headers.size)
+        val values = headers.values("Content-Type")
+        assertTrue(values.contains("application/json"))
+        assertTrue(values.contains("text/html"))
+        assertTrue(values.contains("application/xml"))
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenSameNameDifferentValuesShouldKeepAll() {
+        val plainHeaders = listOf(
+            createPlainHeader("Accept", "text/html"),
+            createPlainHeader("Accept", "application/json"),
+            createPlainHeader("Accept", "text/plain")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(3, headers.size)
+        val accepts = headers.values("Accept")
+        assertEquals(3, accepts.size)
+        assertTrue(accepts.contains("text/html"))
+        assertTrue(accepts.contains("application/json"))
+        assertTrue(accepts.contains("text/plain"))
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenComplexScenarioShouldHandleAllCasesCorrectly() {
+        val plainHeaders = listOf(
+            createPlainHeader("Content-Type", "application/json"),
+            createPlainHeader("Set-Cookie", "session=abc"),
+            createPlainHeader("Set-Cookie", "token=xyz"),
+            createPlainHeader("Set-Cookie", "session=abc"),
+            createPlainHeader("X-Robots-Tag", "noindex, nofollow"),
+            createPlainHeader("X-Robots-Tag", "noindex, nofollow"),
+            createPlainHeader("Cache-Control", "no-cache"),
+            createPlainHeader("cache-control", "no-cache"),
+            createPlainHeader("Accept", "text/html"),
+            createPlainHeader("Accept", "application/json")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(7, headers.size)
+
+        assertEquals("application/json", headers["Content-Type"])
+
+        val cookies = headers.values("Set-Cookie")
+        assertEquals(2, cookies.size)
+        assertTrue(cookies.contains("session=abc"))
+        assertTrue(cookies.contains("token=xyz"))
+
+        assertEquals("noindex, nofollow", headers["X-Robots-Tag"])
+        assertEquals("no-cache", headers["Cache-Control"])
+
+        val accepts = headers.values("Accept")
+        assertEquals(2, accepts.size)
+        assertTrue(accepts.contains("text/html"))
+        assertTrue(accepts.contains("application/json"))
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenHeadersWithWhitespaceShouldPreserveExactValue() {
+        val plainHeaders = listOf(
+            createPlainHeader("X-Custom", "value with spaces"),
+            createPlainHeader("X-Custom", "value with spaces")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(1, headers.size)
+        assertEquals("value with spaces", headers["X-Custom"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenHeadersWithSpecialCharactersShouldPreserveExactValue() {
+        val plainHeaders = listOf(
+            createPlainHeader("Authorization", "Bearer eyJhbGc..."),
+            createPlainHeader("X-Special", "value=test;path=/;secure")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(2, headers.size)
+        assertEquals("Bearer eyJhbGc...", headers["Authorization"])
+        assertEquals("value=test;path=/;secure", headers["X-Special"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenEmptyHeaderValueShouldHandleCorrectly() {
+        val plainHeaders = listOf(
+            createPlainHeader("X-Empty", ""),
+            createPlainHeader("X-Empty", "")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(1, headers.size)
+        assertEquals("", headers["X-Empty"])
+    }
+
+    @Test
+    fun testBuildHeadersWhenGivenMultipleHeadersWithSomeEmptyValuesShouldHandleCorrectly() {
+        val plainHeaders = listOf(
+            createPlainHeader("X-Test", "value1"),
+            createPlainHeader("X-Test", ""),
+            createPlainHeader("X-Test", "value2"),
+            createPlainHeader("X-Test", "")
+        )
+
+        val headers = buildHeaders(plainHeaders)
+
+        assertEquals(3, headers.size)
+        val values = headers.values("X-Test")
+        assertEquals(3, values.size)
+        assertTrue(values.contains("value1"))
+        assertTrue(values.contains(""))
+        assertTrue(values.contains("value2"))
+    }
+
+    private fun createPlainHeader(name: String, value: String) = AidlNetworkRequest.PlainHeader(name, value)
+}