support default namespace for list api

Author: nianliuu

src/main/java/io/pinecone/commons/IndexInterface.java

@@ -734,8 +734,8 @@ W update(String id, List<Float> values, Struct metadata, String namespace, List<
     default void validateListEndpointParameters(String namespace, String prefix, String paginationToken,
                                                 Integer limit, boolean namespaceRequired, boolean prefixRequired,
                                                 boolean paginationTokenRequired, boolean limitRequired) {
-        if (namespaceRequired && (namespace == null || namespace.isEmpty())) {
-            throw new PineconeValidationException("Namespace cannot be null or empty");
+        if (namespaceRequired && (namespace == null)) {
+            throw new PineconeValidationException("Namespace cannot be null");
         }
         if (prefixRequired && (prefix == null || prefix.isEmpty())) {
             throw new PineconeValidationException("Prefix cannot be null or empty");

src/test/java/io/pinecone/ListEndpointValidationTest.java

@@ -40,12 +40,7 @@ public void testValidateListNamespace() throws IOException {
         PineconeValidationException thrownNullNamespace = assertThrows(PineconeValidationException.class, () -> {
             index.validateListEndpointParameters(null, null, null, null, true, true, true, true);
         });
-        assertEquals("Namespace cannot be null or empty", thrownNullNamespace.getMessage());
-
-        PineconeValidationException thrownEmptyNamespace = assertThrows(PineconeValidationException.class, () -> {
-            index.validateListEndpointParameters("", null, null, null, true, true, true, true);
-        });
-        assertEquals("Namespace cannot be null or empty", thrownEmptyNamespace.getMessage());
+        assertEquals("Namespace cannot be null", thrownNullNamespace.getMessage());
     }
 
     @Test