Add StripeContext object (#2057)

* add stripe context

* clean up context creation

* remove comment

* make context public

* pr feedback

Author: xavdid-stripe

src/main/java/com/stripe/StripeClient.java

@@ -1223,6 +1223,11 @@ public StripeClientBuilder setStripeContext(String context) {
       return this;
     }
 
+    public StripeClientBuilder setStripeContext(StripeContext context) {
+      this.stripeContext = context == null ? null : context.toString();
+      return this;
+    }
+
     public String getStripeContext() {
       return this.stripeContext;
     }

src/main/java/com/stripe/StripeContext.java

@@ -0,0 +1,98 @@
+package com.stripe;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import lombok.EqualsAndHashCode;
+
+/**
+ * The StripeContext class provides an immutable container for interacting with the `Stripe-Context`
+ * header.
+ *
+ * <p>You can use it whenever you're initializing a `StripeClient` or sending `stripe_context` with
+ * a request. It's also found in the `EventNotification.context` property.
+ */
+@EqualsAndHashCode
+public final class StripeContext {
+  private final List<String> segments;
+
+  /** Creates a new StripeContext with no segments. */
+  public StripeContext() {
+    this(null);
+  }
+
+  /**
+   * Creates a new StripeContext with the specified segments.
+   *
+   * @param segments the list of context segments
+   */
+  public StripeContext(List<String> segments) {
+    this.segments =
+        segments == null
+            ? Collections.emptyList()
+            : Collections.unmodifiableList(new ArrayList<>(segments));
+  }
+
+  /**
+   * Returns a new StripeContext with the given segment added to the end.
+   *
+   * @param segment the segment to add
+   * @return a new StripeContext instance with the segment appended
+   */
+  public StripeContext push(String segment) {
+    List<String> newSegments = new ArrayList<>(this.segments);
+    newSegments.add(segment);
+    return new StripeContext(newSegments);
+  }
+
+  /**
+   * Returns a new StripeContext with the last segment removed.
+   *
+   * @return a new StripeContext instance with the last segment removed
+   */
+  public StripeContext pop() {
+    if (segments.isEmpty()) {
+      throw new IllegalStateException("Cannot pop from an empty StripeContext");
+    }
+
+    List<String> newSegments = new ArrayList<>(this.segments);
+    newSegments.remove(newSegments.size() - 1);
+    return new StripeContext(newSegments);
+  }
+
+  /**
+   * Converts the context to a string by joining segments with '/'.
+   *
+   * @return string representation of the context segments joined by '/', `null` if there are no
+   *     segments (useful for clearing context)
+   */
+  @Override
+  public String toString() {
+    return String.join("/", segments);
+  }
+
+  /**
+   * Parse a context string into a StripeContext instance.
+   *
+   * @param contextStr string to parse (segments separated by '/')
+   * @return StripeContext instance with segments from the string
+   */
+  public static StripeContext parse(String contextStr) {
+    if (contextStr == null || contextStr.isEmpty()) {
+      return new StripeContext();
+    }
+
+    List<String> segments = Arrays.asList(contextStr.split("/"));
+    return new StripeContext(segments);
+  }
+
+  /**
+   * Returns an unmodifiable list of the current segments.
+   *
+   * @return the list of segments
+   */
+  public List<String> getSegments() {
+    return segments;
+  }
+}

src/main/java/com/stripe/model/StripeContextDeserializer.java

@@ -0,0 +1,26 @@
+package com.stripe.model;
+
+import com.google.gson.JsonDeserializationContext;
+import com.google.gson.JsonDeserializer;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonParseException;
+import com.stripe.StripeContext;
+import java.lang.reflect.Type;
+
+public class StripeContextDeserializer implements JsonDeserializer<StripeContext> {
+
+  @Override
+  public StripeContext deserialize(
+      JsonElement json, Type typeOfT, JsonDeserializationContext context)
+      throws JsonParseException {
+    if (json == null || json.isJsonNull()) {
+      return null;
+    }
+
+    String contextString = json.getAsString().trim();
+    if (contextString.isEmpty()) {
+      return null;
+    }
+    return StripeContext.parse(contextString);
+  }
+}

src/main/java/com/stripe/model/v2/EventNotification.java

@@ -3,6 +3,7 @@
 import com.google.gson.JsonObject;
 import com.google.gson.annotations.SerializedName;
 import com.stripe.StripeClient;
+import com.stripe.StripeContext;
 import com.stripe.exception.StripeException;
 import com.stripe.model.StripeObject;
 import com.stripe.model.v2.Event.RelatedObject;
@@ -71,7 +72,7 @@ public static class Reason {
 
   /** [Optional] Authentication context needed to fetch the event or related object. */
   @SerializedName("context")
-  public String context;
+  public StripeContext context;
 
   /** [Optional] Reason for the event. */
   @SerializedName("reason")
@@ -98,14 +99,17 @@ public static EventNotification fromJson(String payload, StripeClient client) {
 
     EventNotification e = ApiResource.GSON.fromJson(payload, cls);
     e.client = client;
+
     return e;
   }
 
   private RawRequestOptions getRequestOptions() {
     if (context == null) {
       return null;
     }
-    return new RawRequestOptions.RawRequestOptionsBuilder().setStripeContext(context).build();
+    return new RawRequestOptions.RawRequestOptionsBuilder()
+        .setStripeContext(context.toString())
+        .build();
   }
 
   /* retrieves the full payload for an event. Protected because individual push classes use it, but type it correctly */

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

@@ -1,6 +1,7 @@
 package com.stripe.net;
 
 import com.google.gson.*;
+import com.stripe.StripeContext;
 import com.stripe.exception.InvalidRequestException;
 import com.stripe.model.*;
 import com.stripe.model.v2.EventTypeAdapterFactory;
@@ -54,6 +55,7 @@ private static Gson createGson(boolean shouldSetResponseGetter) {
             .registerTypeAdapter(EphemeralKey.class, new EphemeralKeyDeserializer())
             .registerTypeAdapter(Event.Data.class, new EventDataDeserializer())
             .registerTypeAdapter(Event.Request.class, new EventRequestDeserializer())
+            .registerTypeAdapter(StripeContext.class, new StripeContextDeserializer())
             .registerTypeAdapter(ExpandableField.class, new ExpandableFieldDeserializer())
             .registerTypeAdapter(Instant.class, new InstantDeserializer())
             .registerTypeAdapterFactory(new EventTypeAdapterFactory())

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

@@ -1,5 +1,6 @@
 package com.stripe.net;
 
+import com.stripe.StripeContext;
 import java.net.PasswordAuthentication;
 import java.net.Proxy;
 import java.util.Map;
@@ -81,6 +82,12 @@ public RawRequestOptionsBuilder setStripeContext(String stripeContext) {
       return this;
     }
 
+    @Override
+    public RawRequestOptionsBuilder setStripeContext(StripeContext stripeContext) {
+      super.setStripeContext(stripeContext);
+      return this;
+    }
+
     @Override
     public RawRequestOptionsBuilder setStripeAccount(String stripeAccount) {
       super.setStripeAccount(stripeAccount);

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

@@ -235,6 +235,17 @@ public RequestOptionsBuilder setStripeContext(String context) {
       return this;
     }
 
+    public RequestOptionsBuilder setStripeContext(com.stripe.StripeContext context) {
+      this.stripeContext = context != null ? context.toString() : null;
+      return this;
+    }
+
+    /**
+     * Empties the current builder value for StripeContext, which will defer to the client options.
+     *
+     * <p>To send no context at all, call `setContext(new StripeContext())`or set the context to an
+     * empty string.
+     */
     public RequestOptionsBuilder clearStripeContext() {
       this.stripeContext = null;
       return this;
@@ -472,15 +483,28 @@ static RequestOptions merge(StripeResponseGetterOptions clientOptions, RequestOp
           clientOptions.getProxyCredential() // proxyCredential
           );
     }
+
+    // callers need to be able to explicitly unset context per-request
+    // an empty StripeContext serializes to a "", so check for that and empty context out if it's
+    // there.
+    String stripeContext;
+    if (options.getStripeContext() != null) {
+      String requestContext = options.getStripeContext().trim();
+      if (requestContext.isEmpty()) {
+        stripeContext = null;
+      } else {
+        stripeContext = requestContext;
+      }
+    } else {
+      stripeContext = clientOptions.getStripeContext();
+    }
     return new RequestOptions(
         options.getAuthenticator() != null
             ? options.getAuthenticator()
             : clientOptions.getAuthenticator(),
         options.getClientId() != null ? options.getClientId() : clientOptions.getClientId(),
         options.getIdempotencyKey(),
-        options.getStripeContext() != null
-            ? options.getStripeContext()
-            : clientOptions.getStripeContext(),
+        stripeContext,
         options.getStripeAccount() != null
             ? options.getStripeAccount()
             : clientOptions.getStripeAccount(),

src/test/java/com/stripe/StripeClientTest.java

@@ -248,7 +248,7 @@ public void parsesEventNotificationWithRelatedObject()
     assertEquals("evt_234", eventNotification.getId());
     assertEquals("v1.billing.meter.error_report_triggered", eventNotification.getType());
     assertEquals(Instant.parse("2022-02-15T00:27:45.330Z"), eventNotification.created);
-    assertEquals("org_123", eventNotification.context);
+    assertEquals("org_123", eventNotification.getContext().toString());
     assertInstanceOf(V1BillingMeterErrorReportTriggeredEventNotification.class, eventNotification);
     assertEquals("request", eventNotification.getReason().getType());
     assertEquals("abc123", eventNotification.getReason().getRequest().getId());