Prototype: Complex attributes (Option A)

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

@@ -51,6 +51,11 @@ static AttributeKey<Double> doubleKey(String key) {
     return InternalAttributeKeyImpl.create(key, AttributeType.DOUBLE);
   }
 
+  /** Returns a new AttributeKey for {@link Attributes} (Map) valued attributes. */
+  static AttributeKey<Attributes> mapKey(String key) {
+    return InternalAttributeKeyImpl.create(key, AttributeType.MAP);
+  }
+
   /** Returns a new AttributeKey for List&lt;String&gt; valued attributes. */
   static AttributeKey<List<String>> stringArrayKey(String key) {
     return InternalAttributeKeyImpl.create(key, AttributeType.STRING_ARRAY);
@@ -70,4 +75,14 @@ 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 List&lt;Attributes&gt; (List of Maps) valued attributes. */
+  static AttributeKey<List<Attributes>> mapArrayKey(String key) {
+    return InternalAttributeKeyImpl.create(key, AttributeType.MAP_ARRAY);
+  }
+
+  /** Returns a new AttributeKey for generic {@link Value} valued attributes. */
+  static AttributeKey<Value<?>> valueKey(String key) {
+    return InternalAttributeKeyImpl.create(key, AttributeType.VALUE);
+  }
 }

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

@@ -14,8 +14,11 @@ public enum AttributeType {
   BOOLEAN,
   LONG,
   DOUBLE,
+  MAP,
   STRING_ARRAY,
   BOOLEAN_ARRAY,
   LONG_ARRAY,
-  DOUBLE_ARRAY
+  DOUBLE_ARRAY,
+  MAP_ARRAY,
+  VALUE
 }

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

@@ -12,8 +12,11 @@
 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;
+import static io.opentelemetry.api.common.AttributeKey.valueKey;
 
 import java.util.Arrays;
 import java.util.List;
@@ -91,6 +94,21 @@ default AttributesBuilder put(String key, boolean value) {
     return put(booleanKey(key), value);
   }
 
+  /**
+   * Puts an {@link Attributes} (Map) attribute into this.
+   *
+   * <p>Note: It is strongly recommended to use {@link #put(AttributeKey, Object)}, and pre-allocate
+   * your keys, if possible.
+   *
+   * @return this Builder
+   */
+  default <T> AttributesBuilder put(String key, Attributes value) {
+    if (value == null) {
+      return this;
+    }
+    return put(mapKey(key), value);
+  }
+
   /**
    * Puts a String array attribute into this.
    *
@@ -164,6 +182,36 @@ default AttributesBuilder put(String key, boolean... value) {
     return put(booleanArrayKey(key), toList(value));
   }
 
+  /**
+   * Puts an {@link Attributes} array (List of Maps) attribute into this.
+   *
+   * <p>Note: It is strongly recommended to use {@link #put(AttributeKey, Object)}, and pre-allocate
+   * your keys, if possible.
+   *
+   * @return this Builder
+   */
+  default <T> AttributesBuilder put(String key, Attributes... value) {
+    if (value == null) {
+      return this;
+    }
+    return put(mapArrayKey(key), toList(value));
+  }
+
+  /**
+   * Puts a generic ({@link Value}) attribute into this.
+   *
+   * <p>Note: It is strongly recommended to use {@link #put(AttributeKey, Object)}, and pre-allocate
+   * your keys, if possible.
+   *
+   * @return this Builder
+   */
+  default AttributesBuilder put(String key, Value<?> value) {
+    if (value == null) {
+      return this;
+    }
+    return put(valueKey(key), value);
+  }
+
   /**
    * Puts all the provided attributes into this Builder.
    *