fix map structured args in logstash (open-telemetry#15341)

Author: zeitlinger

instrumentation/logback/logback-appender-1.0/library/src/logstashStructuredArgsTest/java/io/opentelemetry/instrumentation/logback/appender/v1_0/LogstashStructuredArgsTest.java

@@ -9,6 +9,8 @@
 
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.instrumentation.testing.junit.LibraryInstrumentationExtension;
+import java.util.HashMap;
+import java.util.Map;
 import net.logstash.logback.argument.StructuredArguments;
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;
@@ -90,4 +92,17 @@ void structuredArgumentsWithTypedValues() {
                 equalTo(AttributeKey.longKey("timestamp"), timestamp),
                 equalTo(AttributeKey.booleanKey("session_active"), true)));
   }
+
+  @Test
+  void logWithStructuredArgument() {
+    Map<String, Object> eventData = new HashMap<>();
+    eventData.put("foo", "bar");
+    logger.info("message: {}", StructuredArguments.entries(eventData));
+
+    testing.waitAndAssertLogRecords(
+        logRecord ->
+            logRecord
+                .hasBody("message: {foo=bar}")
+                .hasAttributesSatisfying(equalTo(AttributeKey.stringKey("foo"), "bar")));
+  }
 }

instrumentation/logback/logback-appender-1.0/library/src/main/java/io/opentelemetry/instrumentation/logback/appender/v1_0/internal/LoggingEventMapper.java

@@ -640,7 +640,7 @@ private static boolean supportsLogstashStructuredArguments() {
   private void captureLogstashStructuredArguments(LogRecordBuilder builder, Object[] arguments) {
     for (Object argument : arguments) {
       if (isLogstashStructuredArgument(argument)) {
-        captureLogstashStructuredArgument(builder, argument);
+        captureLogstashMarker(builder, argument);
       }
     }
   }
@@ -649,15 +649,8 @@ private void captureLogstashStructuredArguments(LogRecordBuilder builder, Object
   private static boolean isLogstashStructuredArgument(Object argument) {
     // StructuredArguments implement the marker interface, so we can check for it
     // without importing the class directly (which may not be available at runtime)
-    return argument instanceof SingleFieldAppendingMarker;
-  }
-
-  @NoMuzzle
-  private void captureLogstashStructuredArgument(LogRecordBuilder builder, Object argument) {
-    // StructuredArguments created by v() or keyValue() extend SingleFieldAppendingMarker
-    // which has getFieldName() and provides field value via reflection
-    SingleFieldAppendingMarker marker = (SingleFieldAppendingMarker) argument;
-    captureLogstashMarker(builder, marker);
+    return argument instanceof SingleFieldAppendingMarker
+        || argument instanceof MapEntriesAppendingMarker;
   }
 
   private interface FieldReader {