feat: add pluggable Base64Codec interface for Android compatibility by typotter · Pull Request #223 · Eppo-exp/sdk-common-jdk

typotter · 2026-02-19T05:30:43Z

Motivation and Context

java.util.Base64 is only available on Android API 26+ (Android 8.0 Oreo). The Android SDK needs to use android.util.Base64 for compatibility with older devices. This change introduces a pluggable Base64 codec interface that allows platform-specific implementations.

Reference: Eppo-exp/android-sdk#188

Description

Added Base64Codec public interface in Utils.java with base64Encode(String) and base64Decode(String) methods
Added setBase64Codec(Base64Codec) static method to allow consumers to inject custom implementations
Created DefaultBase64Codec private inner class that uses java.util.Base64 (existing behavior)
Modified existing base64Encode() and base64Decode() static methods to delegate to the codec instance
Removed duplicate base64Decode implementation from FlagConfigResponseDeserializer.java
Backward compatible - existing code continues to work without changes

How has this been documented?

Interface and setter method have Javadoc comments
Code is self-documenting with clear naming conventions

How has this been tested?

Added testCustomBase64Codec() to verify custom codec injection works correctly
Added testBase64EncodeDecodeDefault() to verify default codec behavior including null handling and round-trip encoding
Added @AfterEach reset method to ensure test isolation
All existing tests continue to pass
Ran ./gradlew spotlessApply and ./gradlew check successfully

…er to take same

- EppoConfigurationRequest: @NotNull on getters - EppoConfigurationRequestFactory: @NotNull on factory method returns - EppoConfigurationResponse: @Nullable/@NotNull on constructor, factory methods, and getters - ConfigurationParser: @NotNull on method params and returns - EppoConfigurationClient: @NotNull on get() method

… the ConfigurationRequestor

Add pluggable Base64 codec support to allow platform-specific implementations (e.g., Android SDK using android.util.Base64). - Add public Base64Codec interface with encode/decode methods - Add setBase64Codec() method for custom codec injection - Create DefaultBase64Codec inner class using java.util.Base64 - Delegate existing base64Encode/base64Decode methods to codec

Remove duplicate base64Decode implementation from FlagConfigResponseDeserializer and use the centralized version from Utils via static import.

Add tests to verify Base64 codec pluggability: - testCustomBase64Codec: verifies custom codec injection works - testBase64EncodeDecodeDefault: verifies default codec behavior - @AfterEach reset method ensures test isolation

- Add volatile keyword to base64Codec field for thread safety - Add null check in setBase64Codec() throwing IllegalArgumentException - Add resetBase64Codec() method for test cleanup - Use explicit StandardCharsets.UTF_8 in base64Decode - Add test for null codec rejection - Simplify test reset to use resetBase64Codec method

Copilot

Pull request overview

This PR introduces a pluggable Base64 codec interface to enable Android compatibility. The java.util.Base64 class is only available on Android API 26+, so this change allows platform-specific implementations (e.g., using android.util.Base64 for older Android versions) to be injected at runtime.

Changes:

Added Base64Codec public interface with encoding/decoding methods and a setter for custom implementations
Refactored existing Base64 logic into a DefaultBase64Codec implementation that maintains backward compatibility
Removed duplicate base64Decode implementation from FlagConfigResponseDeserializer to use centralized Utils method
Added comprehensive test coverage for custom codec injection, default behavior, and null handling

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
src/main/java/cloud/eppo/Utils.java	Added Base64Codec interface, setBase64Codec() setter, resetBase64Codec() for testing, and DefaultBase64Codec implementation with improved charset handling
eppo-sdk-common/src/main/java/cloud/eppo/ufc/dto/adapters/FlagConfigResponseDeserializer.java	Removed duplicate base64Decode implementation in favor of centralized Utils method
src/test/java/cloud/eppo/UtilsTest.java	Added comprehensive tests for custom codec injection, default behavior, null handling, and test isolation

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aarsilv

Nice! Approving with minor comments

aarsilv · 2026-02-21T02:05:03Z

+            "zero byte output from Base64; if not running on Android hardware be sure to use"
+                + " RobolectricTestRunner");


I wonder if we need something similar for base64Encode

🤔 Looking a little wider at it, we're only actually using the encode method in tests. I'd prefer to keep the Codec here just in case prod code needs to encode in the future we don't have to make a breaking change to add it.

aarsilv · 2026-02-21T02:05:49Z

 public class UtilsTest {
+
+  @AfterEach
+  void resetCodec() {


any reason these are package level instead of class? (e.g., why no public keyword here?)

package-private is enough for JUnit to find them (uses reflection/annotation to find the methods)

aarsilv · 2026-02-21T02:06:09Z

+    assertEquals("encoded:test", Utils.base64Encode("test"));
+    assertTrue(encodeCalled.get());
+
+    assertEquals("decoded:test", Utils.base64Decode("test"));
+    assertTrue(decodeCalled.get());


typotter added 30 commits February 11, 2026 09:28

feat: request, response, client, factory

80d9336

return BanditParamsResponse from the parser and create a config build…

67876be

…er to take same

drop serialize methods

1428354

update javadocs

f3cd362

lint

d4161e9

lint

29cbce5

Add json value unwrapping to Parser interface

74ff8fc

common module extraction with default parser and http client

cfe4eda

build deps

99d57e2

adust to parser interface

2a86c3d

temp: exlcude duplicates

3db6b18

implement unwrapper

2637c4e

j8

8ce04fb

Optionally use ConfigurationParser and ConfigurationRequestClients in…

faed7dc

… the ConfigurationRequestor

Cut over to real implementations in testing

e29f0cd

restore JSON methods for now

b700ec4

Common client (okhttp and Jackson for parsing)

260081c

restore json methods for now

79705cb

tidy

50fbae3

use config.flagsSnapshotId

bd9ca53

merge artifact

350c636

comments

3b117fb

Hard cut to ConfigurationClient

ebffdb7

remove deprecated http client

969ecaa

hard cut to ConfigurationParser

1aff347

remove grafting format field

ef91b6a

drop serialize methods

e8c5521

rip mapper from configuration

779ce0a

fix: j8 compatible failed future

434ad38

typotter added 14 commits February 13, 2026 13:29

update jdocs

a0cf975

parameterize the Json Flag type on the client

ab43c3b

remove the response bytes from the Configuration data object

be2b1c3

removed unused annotations

e32689b

cut over jackson

04e319a

update config docs

83e6b81

remove jackson from bandit action attributes

6b0d94d

re-delegate json parsing/unwrapping

a360488

move okhttp and jackson to test only

8c41131

refactor(deserializer): use Utils.base64Decode instead of duplicate

7825bbf

Remove duplicate base64Decode implementation from FlagConfigResponseDeserializer and use the centralized version from Utils via static import.

test(utils): add tests for Base64Codec pluggability

9c0bc75

Add tests to verify Base64 codec pluggability: - testCustomBase64Codec: verifies custom codec injection works - testBase64EncodeDecodeDefault: verifies default codec behavior - @AfterEach reset method ensures test isolation

make resetCodec package private

9e4d6e0

typotter marked this pull request as ready for review February 19, 2026 06:37

typotter requested a review from aarsilv February 19, 2026 06:37

typotter assigned aarsilv Feb 19, 2026

typotter mentioned this pull request Feb 19, 2026

[config-source] Cleanup #217

Merged

aarsilv requested a review from Copilot February 20, 2026 19:36

Copilot started reviewing on behalf of aarsilv February 20, 2026 19:36 View session

Copilot AI reviewed Feb 20, 2026

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aarsilv approved these changes Feb 21, 2026

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aarsilv assigned typotter and unassigned aarsilv Feb 21, 2026

Base automatically changed from typo/cleanup to feature/v4 February 23, 2026 21:07

merge feature base

54cfb3c

typotter force-pushed the typo/base64codec branch from 6c4391b to 54cfb3c Compare February 23, 2026 21:15

typotter merged commit 1dd488f into feature/v4 Feb 23, 2026
4 checks passed

typotter deleted the typo/base64codec branch February 23, 2026 21:35

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feat: add pluggable Base64Codec interface for Android compatibility#223

feat: add pluggable Base64Codec interface for Android compatibility#223
typotter merged 45 commits intofeature/v4from
typo/base64codec

typotter commented Feb 19, 2026 •

edited

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		"zero byte output from Base64; if not running on Android hardware be sure to use"
		+ " RobolectricTestRunner");

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typotter commented Feb 19, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Motivation and Context

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typotter commented Feb 19, 2026 •

edited

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