fix(aws-android-sdk-lex): prioritize custom lex signer for all regions (#2506)

* fix(aws-android-sdk-lex): prioritize custom lex signer for all regions

* add tests

Author: raphkim

aws-android-sdk-core/src/main/java/com/amazonaws/internal/config/InternalConfig.java

@@ -150,6 +150,8 @@ private static Map<String, SignerConfig> getDefaultServiceRegionSigners() {
         ret.put("s3/ap-south-1", new SignerConfig("AWSS3V4SignerType"));
         ret.put("s3/ap-northeast-2", new SignerConfig("AWSS3V4SignerType"));
         ret.put("s3/eu-west-2", new SignerConfig("AWSS3V4SignerType"));
+        ret.put("lex/eu-central-1", new SignerConfig("AmazonLexV4Signer"));
+        ret.put("lex/cn-north-1", new SignerConfig("AmazonLexV4Signer"));
         return ret;
     }
 

aws-android-sdk-core/src/test/java/com/amazonaws/internal/config/InternalConfigTest.java

@@ -42,6 +42,24 @@ private void s3Assertions(InternalConfig config) {
         assertEquals("AWSS3V4SignerType", signer.getSignerType());
     }
 
+    @Test
+    public void lex() throws Exception {
+        InternalConfig config = new InternalConfig();
+        lexAssertions(config);
+    }
+
+    private void lexAssertions(InternalConfig config) {
+        // lex
+        SignerConfig signer = config.getSignerConfig("lex");
+        assertEquals("AmazonLexV4Signer", signer.getSignerType());
+        // lex EU
+        signer = config.getSignerConfig("lex", "eu-central-1");
+        assertEquals("AmazonLexV4Signer", signer.getSignerType());
+        // lex us-east-1
+        signer = config.getSignerConfig("lex", Regions.US_EAST_1.name());
+        assertEquals("AmazonLexV4Signer", signer.getSignerType());
+    }
+
     @Test
     public void cloudfront() throws Exception {
         InternalConfig config = new InternalConfig();