fix addDimension wrongly adding to defaultDimensions

Author: humanzz

powertools-metrics/src/main/java/software/amazon/lambda/powertools/metrics/internal/EmfMetricsLogger.java

@@ -81,8 +81,6 @@ public void addDimension(software.amazon.lambda.powertools.metrics.model.Dimensi
         dimensionSet.getDimensions().forEach((key, val) -> {
             try {
                 emfDimensionSet.addDimension(key, val);
-                // Update our local copy of default dimensions
-                defaultDimensions.put(key, val);
             } catch (Exception e) {
                 // Ignore dimension errors
             }
@@ -234,7 +232,9 @@ public void flushMetrics(Consumer<Metrics> metricsConsumer) {
         if (namespace != null) {
             metrics.setNamespace(this.namespace);
         }
-        defaultDimensions.forEach(metrics::addDimension);
+        if (!defaultDimensions.isEmpty()) {
+            metrics.setDefaultDimensions(software.amazon.lambda.powertools.metrics.model.DimensionSet.of(defaultDimensions));
+        }
         metadata.forEach(metrics::addMetadata);
 
         metricsConsumer.accept(metrics);

powertools-metrics/src/test/java/software/amazon/lambda/powertools/metrics/internal/EmfMetricsLoggerTest.java

@@ -451,6 +451,7 @@ void shouldFlushMetrics() throws Exception {
         // Given
         metrics.setNamespace("MainNamespace");
         metrics.setDefaultDimensions(DimensionSet.of("CustomDim", "CustomValue"));
+        metrics.addDimension(DimensionSet.of("CustomDim2", "CustomValue2"));
         metrics.addMetadata("CustomMetadata", "MetadataValue");
 
         // When
@@ -469,6 +470,7 @@ void shouldFlushMetrics() throws Exception {
         assertThat(rootNode.get("metric-two").asDouble()).isEqualTo(100);
         assertThat(rootNode.has("CustomDim")).isTrue();
         assertThat(rootNode.get("CustomDim").asText()).isEqualTo("CustomValue");
+        assertThat(rootNode.get("CustomDim2")).isNull();
         assertThat(rootNode.get("_aws").get("CloudWatchMetrics").get(0).get("Namespace").asText())
                 .isEqualTo("MainNamespace");
         assertThat(rootNode.get("_aws").has("CustomMetadata")).isTrue();