Removed last isEmpty for < 1.6 compatibility

pom.xml

@@ -4,7 +4,7 @@
   <groupId>org.scribe</groupId>
   <artifactId>scribe</artifactId>
   <packaging>jar</packaging>
-  <version>1.0.1</version>
+  <version>1.0.2</version>
   <name>OAuth Library</name>
 
   <dependencies>

src/main/java/org/scribe/utils/Preconditions.java

@@ -38,7 +38,7 @@ public class Preconditions
   
   private static void check(boolean requirements, String error)
   {
-    String message = (error == null || error.trim().isEmpty()) ? DEFAULT_MESSAGE : error;
+    String message = (error == null || error.trim().length() <= 0) ? DEFAULT_MESSAGE : error;
     if (!requirements)
     {
       throw new IllegalArgumentException(message);