feat(events): make event serialization usable from another package

The Android SDK's event durability work summarizes and serializes events on the
recording thread, in front of the bounded queue DefaultEventProcessor keeps. It
therefore needs the summarizers and the output formatter directly, and there is
no public way to hand java-sdk-internal a summary that has already been
aggregated.

Today the Android SDK reaches them by declaring a class in this package, which
is a split package across two artifacts. Widening these five declarations lets
it use its own package instead and keeps one implementation of the wire format
rather than a second copy that could drift.

Visibility only. No behavior changes, and every member that was package-private
stays that way except the two constructors and the one method the caller needs:

  EventOutputFormatter            class, constructor, writeOutputEvents
  EventSummarizerInterface        interface
  AggregatedEventSummarizer       class, constructor
  PerContextEventSummarizer       class, constructor
  EventSummarizer                 class only, so EventSummary can be named
  EventSummarizer.EventSummary    class only; an opaque token to a caller

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: abelonogov-ld

lib/shared/internal/src/main/java/com/launchdarkly/sdk/internal/events/AggregatedEventSummarizer.java

@@ -16,10 +16,13 @@
  * Note that the methods of this class are deliberately not thread-safe, because they should
  * always be called from EventProcessor's single message-processing thread.
  */
-final class AggregatedEventSummarizer implements EventSummarizerInterface {
+public final class AggregatedEventSummarizer implements EventSummarizerInterface {
   private final EventSummarizer summarizer;
 
-  AggregatedEventSummarizer() {
+  /**
+   * Creates an instance.
+   */
+  public AggregatedEventSummarizer() {
     this.summarizer = new EventSummarizer();
   }
 

lib/shared/internal/src/main/java/com/launchdarkly/sdk/internal/events/EventOutputFormatter.java

@@ -25,18 +25,33 @@
  * handling of context data and private attribute redaction is implemented in EventContextFormatter
  * and tested in more detail in EventContextFormatterTest.
  */
-final class EventOutputFormatter {
+public final class EventOutputFormatter {
   private final EventContextFormatter contextFormatter;
   private final boolean redactAnonymousAllEvents;
 
-  EventOutputFormatter(EventsConfiguration config) {
+  /**
+   * Creates an instance.
+   *
+   * @param config the events configuration; only the private-attribute settings affect the output
+   */
+  public EventOutputFormatter(EventsConfiguration config) {
     this.contextFormatter = new EventContextFormatter(
         config.allAttributesPrivate,
         config.privateAttributes.toArray(new AttributeRef[config.privateAttributes.size()]));
     this.redactAnonymousAllEvents = config.redactAnonymousAllEvents;
   }
 
-  int writeOutputEvents(Event[] events, List<EventSummarizer.EventSummary> summaries, Writer writer) throws IOException {
+  /**
+   * Writes events and summaries as the JSON array that makes up a request body.
+   *
+   * @param events the individual events to write
+   * @param summaries the summaries to write; empty ones are skipped
+   * @param writer where to write the JSON
+   * @return how many output events were written, counting each summary as one
+   * @throws IOException if the writer failed
+   */
+  public int writeOutputEvents(Event[] events, List<EventSummarizer.EventSummary> summaries, Writer writer)
+      throws IOException {
     int count = 0;
     JsonWriter jsonWriter = new JsonWriter(writer);
     jsonWriter.beginArray();

lib/shared/internal/src/main/java/com/launchdarkly/sdk/internal/events/EventSummarizer.java

@@ -14,7 +14,7 @@
  * methods of this class are deliberately not thread-safe, because they should always
  * be called from EventProcessor's single message-processing thread.
  */
-final class EventSummarizer {
+public final class EventSummarizer {
   private EventSummary eventsState;
   private final LDContext context; // nullable - only set for per-context summarization
 
@@ -85,7 +85,10 @@ void clear() {
     eventsState = new EventSummary(context);
   }
 
-  static final class EventSummary {
+  /**
+   * A snapshot of the evaluations counted since the last reset.
+   */
+  public static final class EventSummary {
     final Map<String, FlagInfo> counters;
     long startDate;
     long endDate;

lib/shared/internal/src/main/java/com/launchdarkly/sdk/internal/events/EventSummarizerInterface.java

@@ -13,7 +13,7 @@
  * Note that implementations are deliberately not thread-safe, as they should always
  * be called from EventProcessor's single message-processing thread.
  */
-interface EventSummarizerInterface {
+public interface EventSummarizerInterface {
   /**
    * Adds information about an evaluation to the summary.
    *

lib/shared/internal/src/main/java/com/launchdarkly/sdk/internal/events/PerContextEventSummarizer.java

@@ -19,10 +19,13 @@
  * Note that the methods of this class are deliberately not thread-safe, because they should
  * always be called from EventProcessor's single message-processing thread.
  */
-final class PerContextEventSummarizer implements EventSummarizerInterface {
+public final class PerContextEventSummarizer implements EventSummarizerInterface {
   private final Map<LDContext, EventSummarizer> summarizersByContext;
 
-  PerContextEventSummarizer() {
+  /**
+   * Creates an instance.
+   */
+  public PerContextEventSummarizer() {
     this.summarizersByContext = new HashMap<>();
   }