Add a dynamically-configured list of allowed country codes for payments.

service/src/main/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfiguration.java

@@ -30,6 +30,10 @@ public class DynamicConfiguration {
   @Valid
   private DynamicMessageRateConfiguration messageRate = new DynamicMessageRateConfiguration();
 
+  @JsonProperty
+  @Valid
+  private DynamicPaymentsConfiguration payments = new DynamicPaymentsConfiguration();
+
   @JsonProperty
   private Set<String> featureFlags = Collections.emptySet();
 
@@ -59,6 +63,10 @@ public class DynamicConfiguration {
     return messageRate;
   }
 
+  public DynamicPaymentsConfiguration getPaymentsConfiguration() {
+    return payments;
+  }
+
   public Set<String> getActiveFeatureFlags() {
     return featureFlags;
   }

service/src/main/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicPaymentsConfiguration.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.configuration.dynamic;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import java.util.Collections;
+import java.util.Set;
+
+public class DynamicPaymentsConfiguration {
+
+  @JsonProperty
+  private Set<String> allowedCountryCodes = Collections.emptySet();
+
+  public Set<String> getAllowedCountryCodes() {
+    return allowedCountryCodes;
+  }
+}

service/src/test/java/org/whispersystems/textsecuregcm/configuration/dynamic/DynamicConfigurationTest.java

@@ -252,4 +252,28 @@ class DynamicConfigurationTest {
       assertEquals(List.of("2135551212", "2135551313"), config.getNumbers());
     }
   }
+
+  @Test
+  public void testParsePaymentsConfiguration() throws JsonProcessingException {
+    {
+      final String emptyConfigYaml = "test: true";
+      final DynamicConfiguration emptyConfig = DynamicConfigurationManager.OBJECT_MAPPER
+          .readValue(emptyConfigYaml, DynamicConfiguration.class);
+
+      assertTrue(emptyConfig.getPaymentsConfiguration().getAllowedCountryCodes().isEmpty());
+    }
+
+    {
+      final String paymentsConfigYaml =
+          "payments:\n"
+              + "  allowedCountryCodes:\n"
+              + "    - 44";
+
+      final DynamicPaymentsConfiguration config = DynamicConfigurationManager.OBJECT_MAPPER
+          .readValue(paymentsConfigYaml, DynamicConfiguration.class)
+          .getPaymentsConfiguration();
+
+      assertEquals(Set.of("44"), config.getAllowedCountryCodes());
+    }
+  }
 }