[Prototype] How to support complex attributes in logs/events? (Option A)

api/all/src/main/java/io/opentelemetry/api/common/AttributeKey.java

@@ -65,4 +65,24 @@ static AttributeKey<List<Long>> longArrayKey(String key) {
   static AttributeKey<List<Double>> doubleArrayKey(String key) {
     return InternalAttributeKeyImpl.create(key, AttributeType.DOUBLE_ARRAY);
   }
+
+  /**
+   * Returns a new AttributeKey for map valued attributes.
+   *
+   * <p>IMPORTANT: map valued attributes are only supported by Logs. Spans and Metrics do not
+   * support map valued attributes.
+   */
+  static AttributeKey<Attributes> mapKey(String key) {
+    return InternalAttributeKeyImpl.create(key, AttributeType.MAP);
+  }
+
+  /**
+   * Returns a new AttributeKey for List&lt;Attributes&gt; valued attributes.
+   *
+   * <p>IMPORTANT: {@code List&lt;Attributes&gt;} valued attributes are only supported by Logs.
+   * Spans and Metrics do not support {@code List&lt;Attributes&gt;} valued attributes.
+   */
+  static AttributeKey<List<Attributes>> mapArrayKey(String key) {
+    return InternalAttributeKeyImpl.create(key, AttributeType.MAP_ARRAY);
+  }
 }

api/all/src/main/java/io/opentelemetry/api/common/AttributeType.java

@@ -17,5 +17,7 @@ public enum AttributeType {
   STRING_ARRAY,
   BOOLEAN_ARRAY,
   LONG_ARRAY,
-  DOUBLE_ARRAY
+  DOUBLE_ARRAY,
+  MAP,
+  MAP_ARRAY
 }

api/all/src/main/java/io/opentelemetry/api/common/AttributesBuilder.java

@@ -12,6 +12,8 @@
 import static io.opentelemetry.api.common.AttributeKey.doubleKey;
 import static io.opentelemetry.api.common.AttributeKey.longArrayKey;
 import static io.opentelemetry.api.common.AttributeKey.longKey;
+import static io.opentelemetry.api.common.AttributeKey.mapArrayKey;
+import static io.opentelemetry.api.common.AttributeKey.mapKey;
 import static io.opentelemetry.api.common.AttributeKey.stringArrayKey;
 import static io.opentelemetry.api.common.AttributeKey.stringKey;
 
@@ -86,6 +88,24 @@ default AttributesBuilder put(String key, boolean value) {
     return put(booleanKey(key), value);
   }
 
+  /**
+   * Puts a map into this. If {@code AttributesBuilder} previously contained a value for the key,
+   * the old value is replaced by the specified map.
+   *
+   * <p>Note: It is strongly recommended to use {@link #put(AttributeKey, Object)}, and pre-allocate
+   * your keys, if possible.
+   *
+   * <p>IMPORTANT: maps are only supported by Logs. Spans and Metrics do not support maps.
+   *
+   * @return this Builder
+   */
+  default AttributesBuilder put(String key, Attributes attributes) {
+    if (attributes == null) {
+      return this;
+    }
+    return put(mapKey(key), attributes);
+  }
+
   /**
    * Puts a String array attribute into this.
    *
@@ -159,6 +179,25 @@ default AttributesBuilder put(String key, boolean... value) {
     return put(booleanArrayKey(key), toList(value));
   }
 
+  /**
+   * Puts an array of maps into this. If {@code AttributesBuilder} previously contained a value for
+   * the key, the old value is replaced by the specified array of maps.
+   *
+   * <p>Note: It is strongly recommended to use {@link #put(AttributeKey, Object)}, and pre-allocate
+   * your keys, if possible.
+   *
+   * <p>IMPORTANT: arrays of maps are only supported by Logs. Spans and Metrics do not support
+   * arrays of maps.
+   *
+   * @return this Builder
+   */
+  default AttributesBuilder put(String key, Attributes... value) {
+    if (value == null) {
+      return this;
+    }
+    return put(mapArrayKey(key), Arrays.asList(value));
+  }
+
   /**
    * Puts all the provided attributes into this Builder.
    *