remove code and add test

Author: atoulme

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/EmptyMetricStorage.java

@@ -40,9 +40,6 @@ public void recordLong(long value, Attributes attributes, Context context) {}
   @Override
   public void recordDouble(double value, Attributes attributes, Context context) {}
 
-  @Override
-  public void remove(Attributes attributes, Context context) {}
-
   @Override
   public boolean isEnabled() {
     return false;

sdk/metrics/src/main/java/io/opentelemetry/sdk/metrics/internal/state/WriteableMetricStorage.java

@@ -24,7 +24,7 @@ public interface WriteableMetricStorage {
   void recordDouble(double value, Attributes attributes, Context context);
 
   /** Remove a measurement. */
-  void remove(Attributes attributes, Context context);
+  default void remove(Attributes attributes, Context context) {}
 
   /**
    * Returns {@code true} if the storage is actively recording measurements, and {@code false}

sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/state/MetricStorageRegistryTest.java

@@ -115,9 +115,6 @@ public void recordLong(long value, Attributes attributes, Context context) {}
     @Override
     public void recordDouble(double value, Attributes attributes, Context context) {}
 
-    @Override
-    public void remove(Attributes attributes, Context context) {}
-
     @Override
     public boolean isEnabled() {
       return true;

sdk/metrics/src/test/java/io/opentelemetry/sdk/metrics/internal/state/SynchronousMetricStorageTest.java

@@ -923,6 +923,20 @@ void enabledThenDisable_recordAndCollect(MemoryMode memoryMode) {
     storage.recordDouble(10d, Attributes.empty(), Context.current());
 
     assertThat(storage.collect(RESOURCE, INSTRUMENTATION_SCOPE_INFO, 0, 10).isEmpty()).isTrue();
+
+    storage.remove(Attributes.empty(), Context.current());
+
+    storage.setEnabled(true);
+
+    storage.recordDouble(10d, Attributes.empty(), Context.current());
+
+    storage.setEnabled(false);
+
+    storage.remove(Attributes.empty(), Context.current());
+
+    storage.setEnabled(true);
+
+    assertThat(storage.collect(RESOURCE, INSTRUMENTATION_SCOPE_INFO, 0, 10).isEmpty()).isFalse();
   }
 
   @ParameterizedTest