Use snake_case for capture telemetry configuration

Author: ygree

internal-api/src/main/java/datadog/trace/api/ConfigSetting.java

@@ -89,6 +89,10 @@ public ConfigSetting(String key, Object value, ConfigOrigin origin) {
     this.origin = origin;
   }
 
+  public String normalizedKey() {
+    return key.toLowerCase().replace(".", "_");
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) return true;

telemetry/src/main/java/datadog/telemetry/TelemetryRequestBody.java

@@ -216,7 +216,7 @@ public void beginConfiguration() throws IOException {
 
   public void writeConfiguration(ConfigSetting configSetting) throws IOException {
     bodyWriter.beginObject();
-    bodyWriter.name("name").value(configSetting.key);
+    bodyWriter.name("name").value(configSetting.normalizedKey());
     bodyWriter.setSerializeNulls(true);
     bodyWriter.name("value").jsonValue(configSetting.value);
     bodyWriter.setSerializeNulls(false);

telemetry/src/test/groovy/datadog/telemetry/TelemetryRequestBodySpecification.groovy

@@ -77,6 +77,24 @@ class TelemetryRequestBodySpecification extends Specification {
       '{"name":"null","value":null,"origin":"default"}]'
   }
 
+  def 'use snake_case for setting keys'() {
+    setup:
+    TelemetryRequestBody req = new TelemetryRequestBody(RequestType.APP_CLIENT_CONFIGURATION_CHANGE)
+
+    when:
+    req.beginRequest(false)
+    // exclude request header to simplify assertion
+    drainToString(req)
+
+    then:
+    req.beginConfiguration()
+    req.writeConfiguration(ConfigSetting.of("this.is.a.key", "value", ConfigOrigin.REMOTE))
+    req.endConfiguration()
+
+    then:
+    drainToString(req) == ',"configuration":[{"name":"this_is_a_key","value":"value","origin":"remote_config"}]'
+  }
+
   def 'add debug flag'() {
     setup:
     TelemetryRequestBody req = new TelemetryRequestBody(RequestType.APP_STARTED)