fix: Remove default value handling (#1353)

This is done in favor of explicit `optional` field handling in the generator.

Author: vam-google

gax-httpjson/src/main/java/com/google/api/gax/httpjson/ProtoRestSerializer.java

@@ -101,9 +101,6 @@ RequestT fromJson(InputStream message, Charset messageCharset, Message.Builder b
    * @param fieldValue a field value
    */
   public void putPathParam(Map<String, String> fields, String fieldName, Object fieldValue) {
-    if (isDefaultValue(fieldName, fieldValue)) {
-      return;
-    }
     fields.put(fieldName, String.valueOf(fieldValue));
   }
 
@@ -116,11 +113,6 @@ public void putPathParam(Map<String, String> fields, String fieldName, Object fi
    * @param fieldValue a field value
    */
   public void putQueryParam(Map<String, List<String>> fields, String fieldName, Object fieldValue) {
-    // Avoids empty query parameter
-    if (isDefaultValue(fieldName, fieldValue)) {
-      return;
-    }
-
     ImmutableList.Builder<String> paramValueList = ImmutableList.builder();
     if (fieldValue instanceof List<?>) {
       for (Object fieldValueItem : (List<?>) fieldValue) {
@@ -142,15 +134,4 @@ public void putQueryParam(Map<String, List<String>> fields, String fieldName, Ob
   public String toBody(String fieldName, RequestT fieldValue) {
     return toJson(fieldValue);
   }
-
-  private boolean isDefaultValue(String fieldName, Object fieldValue) {
-    // TODO: Revisit this approach to ensure proper default-value handling as per design.
-    if (fieldValue instanceof Number) {
-      return ((Number) fieldValue).longValue() == 0L;
-    } else if (fieldValue instanceof String) {
-      return ((String) fieldValue).isEmpty();
-    }
-
-    return false;
-  }
 }

gax-httpjson/src/test/java/com/google/api/gax/httpjson/ProtoMessageRequestFormatterTest.java

@@ -98,6 +98,7 @@ public void getQueryParamNames() {
     Map<String, List<String>> queryParamNames = formatter.getQueryParamNames(field);
     Map<String, List<String>> expected = new HashMap<>();
     expected.put("number", Arrays.asList("2"));
+    expected.put("typeUrl", Arrays.asList(""));
     Truth.assertThat(queryParamNames).isEqualTo(expected);
   }
 

gax-httpjson/src/test/java/com/google/api/gax/httpjson/ProtoRestSerializerTest.java

@@ -115,7 +115,9 @@ public void putPathParam() {
 
     Map<String, String> expectedFields = new HashMap<>();
     expectedFields.put("optName1", "1");
+    expectedFields.put("optName2", "0");
     expectedFields.put("optName3", "three");
+    expectedFields.put("optName4", "");
 
     Truth.assertThat(fields).isEqualTo(expectedFields);
   }
@@ -131,7 +133,9 @@ public void putQueryParam() {
 
     Map<String, List<String>> expectedFields = new HashMap<>();
     expectedFields.put("optName1", Arrays.asList("1"));
+    expectedFields.put("optName2", Arrays.asList("0"));
     expectedFields.put("optName3", Arrays.asList("three"));
+    expectedFields.put("optName4", Arrays.asList(""));
     expectedFields.put("optName5", Arrays.asList("four", "five"));
 
     Truth.assertThat(fields).isEqualTo(expectedFields);