Update v2 array parameter serialization to use indexed format (#2110)

* Update v2 array parameter serialization to use indexed format

Change array parameter serialization for v2 endpoints to use indexed
format (e.g., ?include[0]=foo&include[1]=bar) instead of the repeated
parameter format (e.g., ?include=foo&include=bar). This aligns v2
behavior with v1 for consistency.

Changes:
- Modified FormEncoder.java flattenParamsCollection to always use indexed format
- Updated tests to expect indexed format for v2 arrays

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>
Committed-By-Agent: claude

* Remove references to arraysAsRepeated

* Format code

* Remove deprecated function

* Fix formatting

---------

Co-authored-by: Claude <[email protected]>
Co-authored-by: Ramya Rao <[email protected]>

Author: 3 people

src/main/java/com/stripe/net/FormEncoder.java

@@ -22,7 +22,7 @@ public static HttpContent createHttpContent(Map<String, Object> params) throws I
       return HttpContent.buildFormURLEncodedContent(new ArrayList<KeyValuePair<String, String>>());
     }
 
-    Collection<KeyValuePair<String, Object>> flatParams = flattenParams(params, false);
+    Collection<KeyValuePair<String, Object>> flatParams = flattenParams(params);
 
     // If all parameters have been encoded as strings, then the content can be represented
     // with application/x-www-form-url-encoded encoding. Otherwise, use
@@ -46,24 +46,12 @@ public static HttpContent createHttpContent(Map<String, Object> params) throws I
    * @return The query string.
    */
   public static String createQueryString(Map<String, Object> params) {
-    return FormEncoder.createQueryString(params, false);
-  }
-
-  /**
-   * Creates the HTTP query string for a given map of parameters.
-   *
-   * @param params The map of parameters.
-   * @param arraysAsRepeated Whether to encode arrays as repeated value ({@code a=1&a=2}) defaults
-   *     to brackets encoding ({@code a[]=1,2}).
-   * @return The query string.
-   */
-  public static String createQueryString(Map<String, Object> params, boolean arraysAsRepeated) {
     if (params == null) {
       return "";
     }
 
     Collection<KeyValuePair<String, String>> flatParams =
-        flattenParams(params, arraysAsRepeated).stream()
+        flattenParams(params).stream()
             .filter(kvp -> kvp.getValue() instanceof String)
             .map(kvp -> new KeyValuePair<String, String>(kvp.getKey(), (String) kvp.getValue()))
             .collect(Collectors.toList());
@@ -117,13 +105,10 @@ public static String createQueryString(
    * }</pre>
    *
    * @param params The map of parameters.
-   * @param arraysAsRepeated Whether to encode arrays as repeated value ({@code a=1&a=2}) defaults
-   *     to brackets encoding ({@code a[]=1,2}).
    * @return The flattened list of parameters.
    */
-  public static List<KeyValuePair<String, Object>> flattenParams(
-      Map<String, Object> params, boolean arraysAsRepeated) {
-    return flattenParamsValue(params, null, arraysAsRepeated);
+  public static List<KeyValuePair<String, Object>> flattenParams(Map<String, Object> params) {
+    return flattenParamsValue(params, null);
   }
 
   /**
@@ -157,12 +142,10 @@ private static String urlEncode(String value) {
    *
    * @param value The value for which to create the list of parameters.
    * @param keyPrefix The key under which new keys should be nested, if any.
-   * @param arraysAsRepeated Whether to encode arrays as repeated value ({@code a=1&a=2}) defaults
-   *     to brackets encoding ({@code a[]=1,2}).
    * @return The list of parameters.
    */
   private static List<KeyValuePair<String, Object>> flattenParamsValue(
-      Object value, String keyPrefix, boolean arraysAsRepeated) {
+      Object value, String keyPrefix) {
     List<KeyValuePair<String, Object>> flatParams = null;
 
     // I wish Java had pattern matching :(
@@ -171,7 +154,7 @@ private static List<KeyValuePair<String, Object>> flattenParamsValue(
       flatParams = singleParam(keyPrefix, "");
 
     } else if (value instanceof Map<?, ?>) {
-      flatParams = flattenParamsMap((Map<?, ?>) value, keyPrefix, arraysAsRepeated);
+      flatParams = flattenParamsMap((Map<?, ?>) value, keyPrefix);
 
     } else if (value instanceof String) {
       flatParams = singleParam(keyPrefix, value);
@@ -183,12 +166,12 @@ private static List<KeyValuePair<String, Object>> flattenParamsValue(
       flatParams = singleParam(keyPrefix, value);
 
     } else if (value instanceof Collection<?>) {
-      flatParams = flattenParamsCollection((Collection<?>) value, keyPrefix, arraysAsRepeated);
+      flatParams = flattenParamsCollection((Collection<?>) value, keyPrefix);
 
     } else if (value.getClass().isArray()) {
       Object[] array = getArrayForObject(value);
       Collection<?> collection = Arrays.stream(array).collect(Collectors.toList());
-      flatParams = flattenParamsCollection(collection, keyPrefix, arraysAsRepeated);
+      flatParams = flattenParamsCollection(collection, keyPrefix);
 
     } else if (value.getClass().isEnum()) {
       flatParams =
@@ -211,7 +194,7 @@ private static List<KeyValuePair<String, Object>> flattenParamsValue(
    * @return The list of parameters.
    */
   private static List<KeyValuePair<String, Object>> flattenParamsMap(
-      Map<?, ?> map, String keyPrefix, boolean arraysAsRepeated) {
+      Map<?, ?> map, String keyPrefix) {
     List<KeyValuePair<String, Object>> flatParams = new ArrayList<KeyValuePair<String, Object>>();
     if (map == null) {
       return flatParams;
@@ -223,7 +206,7 @@ private static List<KeyValuePair<String, Object>> flattenParamsMap(
 
       String newPrefix = newPrefix(key, keyPrefix);
 
-      flatParams.addAll(flattenParamsValue(value, newPrefix, arraysAsRepeated));
+      flatParams.addAll(flattenParamsValue(value, newPrefix));
     }
 
     return flatParams;
@@ -236,28 +219,27 @@ private static List<KeyValuePair<String, Object>> flattenParamsMap(
    *
    * @param collection The collection for which to create the list of parameters.
    * @param keyPrefix The key under which new keys should be nested.
-   * @param arraysAsRepeated Whether to encode arrays as repeated value ({@code a=1&a=2}) defaults
-   *     to brackets encoding ({@code a[]=1,2}).
    * @return The list of parameters.
    */
   private static List<KeyValuePair<String, Object>> flattenParamsCollection(
-      Collection<?> collection, String keyPrefix, boolean arraysAsRepeated) {
+      Collection<?> collection, String keyPrefix) {
     List<KeyValuePair<String, Object>> flatParams = new ArrayList<KeyValuePair<String, Object>>();
     if (collection == null) {
       return flatParams;
     }
 
     int index = 0;
     for (Object value : collection) {
-      String newPrefix = arraysAsRepeated ? keyPrefix : String.format("%s[%d]", keyPrefix, index);
-      flatParams.addAll(flattenParamsValue(value, newPrefix, arraysAsRepeated));
+      // Always use indexed format for arrays
+      String newPrefix = String.format("%s[%d]", keyPrefix, index);
+      flatParams.addAll(flattenParamsValue(value, newPrefix));
       index += 1;
     }
 
     /* Because application/x-www-form-urlencoded cannot represent an empty list, convention
      * is to take the list parameter and just set it to an empty string. (E.g. A regular
      * list might look like `a[0]=1&b[1]=2`. Emptying it would look like `a=`.) */
-    if (!arraysAsRepeated && flatParams.isEmpty()) {
+    if (flatParams.isEmpty()) {
       flatParams.add(new KeyValuePair<String, Object>(keyPrefix, ""));
     }
 

src/main/java/com/stripe/net/StripeRequest.java

@@ -71,7 +71,7 @@ private StripeRequest(
       this.params = (params != null) ? Collections.unmodifiableMap(params) : null;
       this.options = (options != null) ? options : RequestOptions.getDefault();
       this.method = method;
-      this.url = buildURL(method, url, params, apiMode);
+      this.url = buildURL(method, url, params);
       this.headers = buildHeaders(method, this.options, this.content, apiMode);
       this.apiMode = apiMode;
     } catch (IOException e) {
@@ -107,7 +107,7 @@ private StripeRequest(
       this.params = (params != null) ? Collections.unmodifiableMap(params) : null;
       this.options = options;
       this.method = method;
-      this.url = buildURL(method, url, params, apiMode);
+      this.url = buildURL(method, url, params);
       this.content = buildContent(method, params, apiMode);
       this.headers = buildHeaders(method, this.options, this.content, apiMode);
       this.apiMode = apiMode;
@@ -219,7 +219,7 @@ public StripeRequest withAdditionalHeader(String name, String value) {
   }
 
   private static URL buildURL(
-      ApiResource.RequestMethod method, String spec, Map<String, Object> params, ApiMode apiMode)
+      ApiResource.RequestMethod method, String spec, Map<String, Object> params)
       throws IOException {
     StringBuilder sb = new StringBuilder();
 
@@ -229,8 +229,7 @@ private static URL buildURL(
     String specQueryString = specUrl.getQuery();
 
     if ((method != ApiResource.RequestMethod.POST) && (params != null)) {
-      String queryString =
-          FormEncoder.createQueryString(params, apiMode == ApiMode.V2 ? true : false);
+      String queryString = FormEncoder.createQueryString(params);
 
       if (queryString != null && !queryString.isEmpty()) {
         if (specQueryString != null && !specQueryString.isEmpty()) {

src/test/java/com/stripe/net/FormEncoderTest.java

@@ -26,10 +26,8 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
-import javax.annotation.Nullable;
 import lombok.AllArgsConstructor;
 import lombok.Data;
-import lombok.RequiredArgsConstructor;
 import org.hamcrest.CoreMatchers;
 import org.junit.jupiter.api.Test;
 
@@ -130,12 +128,10 @@ public void testCreateQueryString() {
     org.junit.Assume.assumeTrue(!System.getProperty("java.version").startsWith("10."));
 
     @Data
-    @RequiredArgsConstructor
     @AllArgsConstructor
     class TestCase {
       private final Map<String, Object> data;
       private final String want;
-      @Nullable private Boolean arrayAsRepeated = false;
     }
 
     List<TestCase> testCases =
@@ -376,18 +372,16 @@ class TestCase {
                         "array", new Object[] {new String[] {"foo", "bar"}, new int[] {1, 2, 3}}),
                     "array[0][0]=foo&array[0][1]=bar&array[1][0]=1&array[1][1]=2&array[1][2]=3"));
 
-            // Array (arrayAsRepeated)
-            add(new TestCase(Collections.singletonMap("array", new String[] {}), "", true));
+            // Array
+            add(new TestCase(Collections.singletonMap("array", new String[] {}), "array="));
             add(
                 new TestCase(
                     Collections.singletonMap("array", new String[] {"1", "2", "3"}),
-                    "array=1&array=2&array=3",
-                    true));
+                    "array[0]=1&array[1]=2&array[2]=3"));
             add(
                 new TestCase(
                     Collections.singletonMap("array", new Object[] {123, "foo"}),
-                    "array=123&array=foo",
-                    true));
+                    "array[0]=123&array[1]=foo"));
             // Collection
             add(
                 new TestCase(
@@ -429,9 +423,7 @@ class TestCase {
         };
 
     for (TestCase testCase : testCases) {
-      assertEquals(
-          testCase.getWant(),
-          FormEncoder.createQueryString(testCase.getData(), testCase.getArrayAsRepeated()));
+      assertEquals(testCase.getWant(), FormEncoder.createQueryString(testCase.getData()));
     }
   }
 
@@ -481,7 +473,7 @@ class TestCase {
         };
 
     for (TestCase testCase : testCases) {
-      assertEquals(testCase.getWant(), FormEncoder.flattenParams(testCase.getData(), false));
+      assertEquals(testCase.getWant(), FormEncoder.flattenParams(testCase.getData()));
     }
   }