Add ReadableSpan#getAttributes (#6382)

docs/apidiffs/current_vs_latest/opentelemetry-sdk-trace.txt

@@ -1,2 +1,4 @@
 Comparing source compatibility of  against 
-No changes.
+***  MODIFIED INTERFACE: PUBLIC ABSTRACT io.opentelemetry.sdk.trace.ReadableSpan  (not serializable)
+	===  CLASS FILE FORMAT VERSION: 52.0 <- 52.0
+	+++  NEW METHOD: PUBLIC(+) io.opentelemetry.api.common.Attributes getAttributes()

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/ReadableSpan.java

@@ -6,6 +6,7 @@
 package io.opentelemetry.sdk.trace;
 
 import io.opentelemetry.api.common.AttributeKey;
+import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.trace.Span;
 import io.opentelemetry.api.trace.SpanContext;
 import io.opentelemetry.api.trace.SpanKind;
@@ -111,4 +112,20 @@ default InstrumentationScopeInfo getInstrumentationScopeInfo() {
    */
   @Nullable
   <T> T getAttribute(AttributeKey<T> key);
+
+  /**
+   * Returns the Span attributes.
+   *
+   * <p>Attributes can be changed during the lifetime of the Span by using {@link
+   * Span#setAttribute}} so this value cannot be cached.
+   *
+   * <p>Note: the implementation of this method performs locking and returns an immutable copy to
+   * ensure thread-safe behavior. If you only need a single attribute it is better to call {@link
+   * #getAttribute(AttributeKey)}.
+   *
+   * @return the Span attributes, or {@link Attributes#empty()} if the span has no attributes.
+   */
+  default Attributes getAttributes() {
+    return Attributes.empty();
+  }
 }

sdk/trace/src/main/java/io/opentelemetry/sdk/trace/SdkSpan.java

@@ -232,6 +232,13 @@ public <T> T getAttribute(AttributeKey<T> key) {
     }
   }
 
+  @Override
+  public Attributes getAttributes() {
+    synchronized (lock) {
+      return attributes == null ? Attributes.empty() : attributes.immutableCopy();
+    }
+  }
+
   @Override
   public boolean hasEnded() {
     synchronized (lock) {

sdk/trace/src/test/java/io/opentelemetry/sdk/trace/SdkSpanTest.java

@@ -339,6 +339,32 @@ void getAttribute() {
     }
   }
 
+  @Test
+  void getAttributes() {
+    SdkSpan span = createTestSpanWithAttributes(attributes);
+    try {
+      assertThat(span.getAttributes())
+          .isEqualTo(
+              Attributes.builder()
+                  .put("MyBooleanAttributeKey", false)
+                  .put("MyStringAttributeKey", "MyStringAttributeValue")
+                  .put("MyLongAttributeKey", 123L)
+                  .build());
+    } finally {
+      span.end();
+    }
+  }
+
+  @Test
+  void getAttributes_Empty() {
+    SdkSpan span = createTestSpan(SpanKind.INTERNAL);
+    try {
+      assertThat(span.getAttributes()).isEqualTo(Attributes.empty());
+    } finally {
+      span.end();
+    }
+  }
+
   @Test
   @SuppressWarnings("deprecation") // Testing deprecated code
   void getInstrumentationLibraryInfo() {