MulticastInst does not use ConfigStore

Problem
-------

`MulticastInst` does not use `ConfigStore`.  See OpenDDS#4134.

Solution
--------

Convert `MulticastInst` to use `ConfigStore`.

* The following members have been replaced with getters and setters:
  - default_to_ipv6
  - port_offset
  - group_address
  - local_address
  - reliable
  - syn_backoff
  - syn_interval
  - syn_timeout
  - nak_depth
  - nak_interval
  - nak_delay_intervals
  - nak_max
  - mak_timeout
  - ttl
  - rcv_buffer_size
  - async_send

dds/DCPS/ConfigStoreImpl.cpp

@@ -398,7 +398,8 @@ ConfigStoreImpl::set(const char* key,
 
 String
 ConfigStoreImpl::get(const char* key,
-                     const String& value) const
+                     const String& value,
+                     bool allow_empty) const
 {
   const ConfigPair cp(key, "");
   String retval = value;
@@ -410,7 +411,7 @@ ConfigStoreImpl::get(const char* key,
   for (size_t idx = 0; idx != samples.size(); ++idx) {
     const ConfigPair& sample = samples[idx];
     const DDS::SampleInfo& info = infos[idx];
-    if (info.valid_data) {
+    if (info.valid_data && (allow_empty || !sample.value().empty())) {
       retval = sample.value();
     }
   }
@@ -502,6 +503,12 @@ namespace {
                      ConfigStoreImpl::NetworkAddressKind kind)
   {
     switch (kind) {
+    case ConfigStoreImpl::Kind_ANY:
+      return value.get_type() == AF_INET
+#ifdef ACE_HAS_IPV6
+        || value.get_type() == AF_INET6
+#endif
+        ;
     case ConfigStoreImpl::Kind_IPV4:
       return value.get_type() == AF_INET;
 #ifdef ACE_HAS_IPV6

dds/DCPS/ConfigStoreImpl.h

@@ -95,6 +95,7 @@ class OpenDDS_Dcps_Export ConfigStoreImpl : public ConfigStore {
   };
 
   enum NetworkAddressKind {
+    Kind_ANY,
     Kind_IPV4
 #ifdef ACE_HAS_IPV6
     , Kind_IPV6
@@ -142,7 +143,8 @@ class OpenDDS_Dcps_Export ConfigStoreImpl : public ConfigStore {
   void set(const char* key,
            const String& value);
   String get(const char* key,
-             const String& value) const;
+             const String& value,
+             bool allow_empty = true) const;
 
   void set(const char* key,
            const TimeDuration& value,

dds/DCPS/transport/multicast/MulticastDataLink.cpp

@@ -54,7 +54,7 @@ MulticastDataLink::MulticastDataLink(const MulticastTransport_rch& transport,
   // A send buffer may be bound to the send strategy to ensure a
   // configured number of most-recent datagrams are retained:
   if (session_factory_->requires_send_buffer()) {
-    const size_t nak_depth = config ? config->nak_depth_ : MulticastInst::DEFAULT_NAK_DEPTH;
+    const size_t nak_depth = config ? config->nak_depth() : MulticastInst::DEFAULT_NAK_DEPTH;
     const size_t default_max_samples = DEFAULT_CONFIG_MAX_SAMPLES_PER_PACKET;
     const size_t max_samples_per_packet = config ? config->max_samples_per_packet() : default_max_samples;
     send_buffer_.reset(new SingleSendBuffer(nak_depth, max_samples_per_packet));
@@ -78,7 +78,7 @@ MulticastDataLink::join(const ACE_INET_Addr& group_address)
     return false;
   }
 
-  const std::string& net_if = cfg->local_address_;
+  const String net_if = cfg->local_address();
 #ifdef ACE_HAS_MAC_OSX
   socket_.opts(ACE_SOCK_Dgram_Mcast::OPT_BINDADDR_NO |
                ACE_SOCK_Dgram_Mcast::DEFOPT_NULLIFACE);
@@ -95,15 +95,15 @@ MulticastDataLink::join(const ACE_INET_Addr& group_address)
 
   ACE_HANDLE handle = this->socket_.get_handle();
 
-  if (!OpenDDS::DCPS::set_socket_multicast_ttl(this->socket_, cfg->ttl_)) {
+  if (!OpenDDS::DCPS::set_socket_multicast_ttl(this->socket_, cfg->ttl())) {
     ACE_ERROR_RETURN((LM_ERROR,
         ACE_TEXT("(%P|%t) ERROR: ")
         ACE_TEXT("MulticastDataLink::join: ")
         ACE_TEXT("OpenDDS::DCPS::set_socket_multicast_ttl failed.\n")),
         false);
   }
 
-  int rcv_buffer_size = ACE_Utils::truncate_cast<int>(cfg->rcv_buffer_size_);
+  int rcv_buffer_size = ACE_Utils::truncate_cast<int>(cfg->rcv_buffer_size());
   if (rcv_buffer_size != 0
       && ACE_OS::setsockopt(handle, SOL_SOCKET,
           SO_RCVBUF,