use library constants

Signed-off-by: Maciej Mierzwa <[email protected]>

src/main/java/com/amazon/dlic/auth/http/saml/HTTPMetadataResolver.java

@@ -20,6 +20,7 @@
 import org.apache.hc.core5.http.ClassicHttpResponse;
 import org.apache.hc.core5.http.Header;
 import org.apache.hc.core5.http.HttpException;
+import org.apache.hc.core5.http.HttpHeaders;
 import org.apache.hc.core5.http.io.entity.EntityUtils;
 import org.apache.http.HttpStatus;
 
@@ -88,8 +89,8 @@ protected byte[] fetchMetadata() throws ResolverException {
 
         try {
             log.debug("{} Attempting to fetch metadata document from '{}'", getLogPrefix(), metadataURI);
-            return httpClient.execute(httpGet, context, response1 -> {
-                final int httpStatusCode = response1.getCode();
+            return httpClient.execute(httpGet, context, response -> {
+                final int httpStatusCode = response.getCode();
                 if (httpStatusCode == HttpStatus.SC_NOT_MODIFIED) {
                     log.debug("{} Metadata document from '{}' has not changed since last retrieval", getLogPrefix(), getMetadataURI());
                     return null;
@@ -100,9 +101,9 @@ protected byte[] fetchMetadata() throws ResolverException {
                     throw new HttpException(errMsg);
                 }
 
-                processConditionalRetrievalHeaders(response1);
+                processConditionalRetrievalHeaders(response);
                 try {
-                    return getMetadataBytesFromResponse(response1);
+                    return getMetadataBytesFromResponse(response);
                 } catch (ResolverException e) {
                     final String errMsg = "Error retrieving metadata from " + metadataURI;
                     throw new HttpException(errMsg, e);
@@ -119,22 +120,22 @@ protected HttpGet buildHttpGet() {
         final HttpGet getMethod = new HttpGet(getMetadataURI());
 
         if (cachedMetadataETag != null) {
-            getMethod.setHeader("If-None-Match", cachedMetadataETag);
+            getMethod.setHeader(HttpHeaders.IF_NONE_MATCH, cachedMetadataETag);
         }
         if (cachedMetadataLastModified != null) {
-            getMethod.setHeader("If-Modified-Since", cachedMetadataLastModified);
+            getMethod.setHeader(HttpHeaders.IF_MODIFIED_SINCE, cachedMetadataLastModified);
         }
 
         return getMethod;
     }
 
     protected void processConditionalRetrievalHeaders(final ClassicHttpResponse response) {
-        Header httpHeader = response.getFirstHeader("ETag");
+        Header httpHeader = response.getFirstHeader(HttpHeaders.ETAG);
         if (httpHeader != null) {
             cachedMetadataETag = httpHeader.getValue();
         }
 
-        httpHeader = response.getFirstHeader("Last-Modified");
+        httpHeader = response.getFirstHeader(HttpHeaders.LAST_MODIFIED);
         if (httpHeader != null) {
             cachedMetadataLastModified = httpHeader.getValue();
         }