make IntegrationSettings.AnalyticsSampleRate not nullable and default to 1.0 (DataDog#324)

Author: lucaspimentel

src/Datadog.Trace/Configuration/IntegrationSettings.cs

@@ -25,7 +25,8 @@ public IntegrationSettings(string integrationName, IConfigurationSource source)
 
             AnalyticsEnabled = source.GetBool(string.Format(ConfigurationKeys.Integrations.AnalyticsEnabled, integrationName));
 
-            AnalyticsSampleRate = source.GetDouble(string.Format(ConfigurationKeys.Integrations.AnalyticsSampleRate, integrationName));
+            AnalyticsSampleRate = source.GetDouble(string.Format(ConfigurationKeys.Integrations.AnalyticsSampleRate, integrationName)) ??
+                                  1.0;
         }
 
         /// <summary>
@@ -49,6 +50,6 @@ public IntegrationSettings(string integrationName, IConfigurationSource source)
         /// Gets or sets a value between 0 and 1 (inclusive)
         /// that determines the sampling rate for this integration.
         /// </summary>
-        public double? AnalyticsSampleRate { get; set; }
+        public double AnalyticsSampleRate { get; set; }
     }
 }

src/Datadog.Trace/Configuration/TracerSettings.cs

@@ -183,7 +183,7 @@ internal bool IsIntegrationEnabled(string name)
         {
             var integrationSettings = Integrations[name];
             var analyticsEnabled = integrationSettings.AnalyticsEnabled ?? (enabledWithGlobalSetting && AnalyticsEnabled);
-            return analyticsEnabled ? integrationSettings.AnalyticsSampleRate : null;
+            return analyticsEnabled ? integrationSettings.AnalyticsSampleRate : (double?)null;
         }
     }
 }