Fix: Allowing Empty UserID as valid field

core-api/src/main/java/com/optimizely/ab/Optimizely.java

@@ -819,10 +819,6 @@ private boolean validateUserId(String userId) {
             logger.error("The user ID parameter must be nonnull.");
             return false;
         }
-        if (userId.trim().isEmpty()) {
-            logger.error("Non-empty user ID required");
-            return false;
-        }
 
         return true;
     }

core-api/src/main/java/com/optimizely/ab/config/ProjectConfig.java

@@ -496,8 +496,7 @@ public boolean setForcedVariation(@Nonnull String experimentKey,
         }
 
         // if the user id is invalid, return false.
-        if (userId == null || userId.trim().isEmpty()) {
-            logger.error("User ID is invalid");
+        if (!validateUserId(userId)) {
             return false;
         }
 
@@ -554,8 +553,7 @@ public boolean setForcedVariation(@Nonnull String experimentKey,
                                                   @Nonnull String userId) {
 
         // if the user id is invalid, return false.
-        if (userId == null || userId.trim().isEmpty()) {
-            logger.error("User ID is invalid");
+        if (!validateUserId(userId)) {
             return null;
         }
 
@@ -587,6 +585,21 @@ public boolean setForcedVariation(@Nonnull String experimentKey,
         return null;
     }
 
+    /**
+     * Helper function to check that the provided userId is valid
+     *
+     * @param userId the userId being validated
+     * @return whether the user ID is valid
+     */
+    private boolean validateUserId(String userId) {
+        if (userId == null) {
+            logger.error("User ID is invalid");
+            return false;
+        }
+
+        return true;
+    }
+
     @Override
     public String toString() {
         return "ProjectConfig{" +

core-api/src/test/java/com/optimizely/ab/OptimizelyTest.java

@@ -1385,7 +1385,7 @@ public void activateUserNoAttributesWithAudiences() throws Exception {
     }
 
     /**
-     * Verify that {@link Optimizely#activate(String, String)} doesn't return a variation when provided an empty string.
+     * Verify that {@link Optimizely#activate(String, String)} return a variation when provided an empty string.
      */
     @Test
     public void activateWithEmptyUserId() throws Exception {
@@ -1397,9 +1397,7 @@ public void activateWithEmptyUserId() throws Exception {
                 .withErrorHandler(new RaiseExceptionErrorHandler())
                 .build();
 
-        logbackVerifier.expectMessage(Level.ERROR, "Non-empty user ID required");
-        logbackVerifier.expectMessage(Level.INFO, "Not activating user for experiment \"" + experimentKey + "\".");
-        assertNull(optimizely.activate(experimentKey, ""));
+        assertNotNull(optimizely.activate(experimentKey, ""));
     }
 
     /**
@@ -2695,7 +2693,7 @@ public void getVariationWithUnknownExperimentKeyAndRaiseExceptionErrorHandler()
     }
 
     /**
-     * Verify that {@link Optimizely#getVariation(String, String)} doesn't return a variation when provided an
+     * Verify that {@link Optimizely#getVariation(String, String)} return a variation when provided an
      * empty string.
      */
     @Test
@@ -2707,8 +2705,7 @@ public void getVariationWithEmptyUserId() throws Exception {
                 .withErrorHandler(new RaiseExceptionErrorHandler())
                 .build();
 
-        logbackVerifier.expectMessage(Level.ERROR, "Non-empty user ID required");
-        assertNull(optimizely.getVariation(experiment.getKey(), ""));
+        assertNotNull(optimizely.getVariation(experiment.getKey(), ""));
     }
 
     /**
@@ -4049,8 +4046,7 @@ public void getEnabledFeatureWithEmptyUserId() throws ConfigParseException{
                 .build());
         ArrayList<String> featureFlags = (ArrayList<String>) spyOptimizely.getEnabledFeatures("",
                 new HashMap<String, String>());
-        logbackVerifier.expectMessage(Level.ERROR, "Non-empty user ID required");
-        assertTrue(featureFlags.isEmpty());
+        assertFalse(featureFlags.isEmpty());
 
     }
 

core-api/src/test/java/com/optimizely/ab/config/ProjectConfigTest.java

@@ -31,11 +31,7 @@
 
 import static java.util.Arrays.asList;
 import static org.hamcrest.CoreMatchers.is;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThat;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.*;
 
 
 import com.optimizely.ab.internal.LogbackVerifier;
@@ -244,12 +240,12 @@ public void getForcedVariationNullUserId() {
 
     @Test
     public void setForcedVariationEmptyUserId() {
-        assertFalse(projectConfig.setForcedVariation("etag1", "", "vtag1"));
+        assertTrue(projectConfig.setForcedVariation("etag1", "", "vtag1"));
     }
 
     @Test
     public void getForcedVariationEmptyUserId() {
-        assertNull(projectConfig.getForcedVariation("etag1", ""));
+        assertNotNull(projectConfig.getForcedVariation("etag1", ""));
     }
 
     /* Invalid Experiement */