Log when MTRServerAttribute not bound to a controller has its value u…

…pdated. (#31973)

This should enable API consumers to more easily figure out why their attribute
updates are not being published.

src/darwin/Framework/CHIP/ServerEndpoint/MTRServerAttribute.mm

@@ -72,14 +72,19 @@ - (nullable instancetype)initWithAttributeID:(NSNumber *)attributeID value:(NSDi
  _parentCluster = app::ConcreteClusterPath(kInvalidEndpointId, kInvalidClusterId);
 
  // Now call setValue to store the value and its serialization.
- if ([self setValue:value] == NO) {
+ if ([self setValueInternal:value logIfNotAssociated:NO] == NO) {
  return nil;
  }
 
  return self;
 }
 
 - (BOOL)setValue:(NSDictionary<NSString *, id> *)value
+{
+ return [self setValueInternal:value logIfNotAssociated:YES];
+}
+
+- (BOOL)setValueInternal:(NSDictionary<NSString *, id> *)value logIfNotAssociated:(BOOL)logIfNotAssociated
 {
  id serializedValue;
  id dataType = value[MTRTypeKey];
@@ -121,7 +126,12 @@ - (BOOL)setValue:(NSDictionary<NSString *, id> *)value
 
  MTRDeviceController * deviceController = _deviceController;
  if (deviceController == nil) {
- // We're not bound to a controller, so safe to directly update _serializedValue.
+ // We're not bound to a controller, so safe to directly update
+ // _serializedValue.
+ if (logIfNotAssociated) {
+ MTR_LOG_DEFAULT("Not publishing value for attribute " ChipLogFormatMEI "; not bound to a controller",
+ ChipLogValueMEI(static_cast<AttributeId>(_attributeID.unsignedLongLongValue)));
+ }
  _serializedValue = serializedValue;
  } else {
  [deviceController asyncDispatchToMatterQueue:^{