Prefer Guava.nullToEmpty and HttpUtils.nullToEmpty

Make HttpUtils.valueOrEmpty static and change method name to
nullToEmpty to mimic Guava.

apis/atmos/src/main/java/org/jclouds/atmos/filters/SignRequest.java

@@ -49,6 +49,7 @@ import org.jclouds.logging.Logger;
 import org.jclouds.util.Strings2;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableMap.Builder;
 import com.google.common.collect.Multimaps;
@@ -167,7 +168,7 @@ public class SignRequest implements HttpRequestFilter {
 
    private void appendPayloadMetadata(HttpRequest request, StringBuilder buffer) {
       buffer.append(
-            utils.valueOrEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
+            Strings.nullToEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
                   .getContentType())).append("\n");
    }
 
@@ -176,7 +177,7 @@ public class SignRequest implements HttpRequestFilter {
       // Only the value is used, not the header
       // name. If a request does not include the header, this is an empty string.
       for (String header : new String[] { "Range" })
-         toSign.append(utils.valueOrEmpty(request.getHeaders().get(header)).toLowerCase()).append("\n");
+         toSign.append(HttpUtils.nullToEmpty(request.getHeaders().get(header)).toLowerCase()).append("\n");
       // Standard HTTP header, in UTC format. Only the date value is used, not the header name.
       toSign.append(request.getFirstHeaderOrNull(HttpHeaders.DATE)).append("\n");
    }

apis/s3/src/main/java/org/jclouds/s3/filters/RequestAuthorizeSignature.java

@@ -62,6 +62,7 @@ import org.jclouds.s3.Bucket;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Predicate;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.Multimap;
@@ -204,14 +205,14 @@ public class RequestAuthorizeSignature implements HttpRequestFilter, RequestSign
       // note that we fall back to headers, and some requests such as ?uploads do not have a
       // payload, yet specify payload related parameters
       buffer.append(
-               request.getPayload() == null ? utils.valueOrEmpty(request.getFirstHeaderOrNull("Content-MD5")) : utils
+               request.getPayload() == null ? Strings.nullToEmpty(request.getFirstHeaderOrNull("Content-MD5")) :
-                        .valueOrEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
+                        HttpUtils.nullToEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
                                  .getContentMD5())).append("\n");
       buffer.append(
-               utils.valueOrEmpty(request.getPayload() == null ? request.getFirstHeaderOrNull(HttpHeaders.CONTENT_TYPE)
+               Strings.nullToEmpty(request.getPayload() == null ? request.getFirstHeaderOrNull(HttpHeaders.CONTENT_TYPE)
                         : request.getPayload().getContentMetadata().getContentType())).append("\n");
       for (String header : FIRST_HEADERS_TO_SIGN)
-         buffer.append(valueOrEmpty(request.getHeaders().get(header))).append("\n");
+         buffer.append(HttpUtils.nullToEmpty(request.getHeaders().get(header))).append("\n");
    }
 
    @VisibleForTesting
@@ -270,8 +271,4 @@ public class RequestAuthorizeSignature implements HttpRequestFilter, RequestSign
          }
       }
    }
-
-   private String valueOrEmpty(Collection<String> collection) {
-      return (collection != null && collection.size() >= 1) ? collection.iterator().next() : "";
-   }
 }

common/azure/src/main/java/org/jclouds/azure/storage/filters/SharedKeyLiteAuthentication.java

@@ -46,6 +46,7 @@ import org.jclouds.logging.Logger;
 import org.jclouds.util.Strings2;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableMap.Builder;
@@ -122,10 +123,10 @@ public class SharedKeyLiteAuthentication implements HttpRequestFilter {
 
    private void appendPayloadMetadata(HttpRequest request, StringBuilder buffer) {
       buffer.append(
-            utils.valueOrEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
+            HttpUtils.nullToEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
                   .getContentMD5())).append("\n");
       buffer.append(
-            utils.valueOrEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
+            Strings.nullToEmpty(request.getPayload() == null ? null : request.getPayload().getContentMetadata()
                   .getContentType())).append("\n");
    }
 
@@ -166,7 +167,7 @@ public class SharedKeyLiteAuthentication implements HttpRequestFilter {
 
    private void appendHttpHeaders(HttpRequest request, StringBuilder toSign) {
       for (String header : FIRST_HEADERS_TO_SIGN)
-         toSign.append(utils.valueOrEmpty(request.getHeaders().get(header))).append("\n");
+         toSign.append(HttpUtils.nullToEmpty(request.getHeaders().get(header))).append("\n");
    }
 
    @VisibleForTesting

core/src/main/java/org/jclouds/http/HttpUtils.java

@@ -399,16 +399,12 @@ public class HttpUtils {
          from.getPayload().release();
    }
 
-   public String valueOrEmpty(String in) {
+   public static String nullToEmpty(byte[] md5) {
-      return in != null ? in : "";
-   }
-
-   public String valueOrEmpty(byte[] md5) {
       return md5 != null ? CryptoStreams.base64(md5) : "";
    }
 
-   public String valueOrEmpty(Collection<String> collection) {
+   public static String nullToEmpty(Collection<String> collection) {
-      return (collection != null && collection.size() >= 1) ? collection.iterator().next() : "";
+      return (collection == null || collection.isEmpty()) ? "" : collection.iterator().next();
    }
 
    public static Long attemptToParseSizeAndRangeFromHeaders(HttpMessage from) throws HttpException {