relaxing reReportToCollector restraint and adding unit test

Author: mhlidd

internal-api/src/main/java/datadog/trace/bootstrap/config/provider/ConfigProvider.java

@@ -627,7 +627,7 @@ private static <T> void reportDefault(String key, T defaultValue) {
   }
 
   /** Helper class to store resolved configuration values with their metadata */
-  private static class ConfigValueResolver<T> {
+  static class ConfigValueResolver<T> {
     final T value;
     final ConfigOrigin origin;
     final int seqId;
@@ -653,7 +653,8 @@ static <T> ConfigValueResolver<T> of(T value, ConfigOrigin origin, int seqId, St
 
     /** Re-reports this resolved value to ConfigCollector with the specified seqId */
     void reReportToCollector(String key, int finalSeqId) {
-      if (value != null && origin != null) {
+      // Source and value should never be null if there is an initialized ConfigValueResolver
+      if (origin != null) {
         ConfigCollector.get().put(key, value, origin, finalSeqId, configId);
       }
     }

internal-api/src/test/groovy/datadog/trace/bootstrap/config/provider/ConfigProviderTest.groovy

@@ -475,4 +475,17 @@ class ConfigProviderTest extends DDSpecification {
     def maxSeqId = [defaultSetting.seqId, envSetting.seqId, jvmSetting.seqId, calculatedSetting.seqId].max()
     calculatedSetting.seqId == maxSeqId
   }
+
+  // NOTE: This is a case that SHOULD never occur. #reReportToCollector(String, int) should only be called with valid origins
+  def "ConfigValueResolver reReportToCollector handles null origin gracefully"() {
+    setup:
+    ConfigCollector.get().collect() // clear previous state
+    ConfigProvider.ConfigValueResolver resolver = ConfigProvider.ConfigValueResolver.of("1")
+
+    when:
+    resolver.reReportToCollector("test.key", 5)
+
+    then:
+    0 * ConfigCollector.get().put(_, _, _, _, _)
+  }
 }