fix: Remove post policy v4 client side validation (#1210)

Author: JesseLovelace

google-cloud-storage/src/main/java/com/google/cloud/storage/PostPolicyV4.java

@@ -21,11 +21,9 @@
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.text.SimpleDateFormat;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
-import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Set;
@@ -54,7 +52,6 @@ private PostPolicyV4(String url, Map<String, String> fields) {
  } catch (URISyntaxException e) {
  throw new IllegalArgumentException(e);
  }
- PostFieldsV4.validateFields(fields);
 
  this.url = url;
  this.fields = Collections.unmodifiableMap(fields);
@@ -93,40 +90,12 @@ public Map<String, String> getFields() {
  */
  public static final class PostFieldsV4 {
  private final Map<String, String> fieldsMap;
- private static final List<String> VALID_FIELDS =
- Arrays.asList(
- "acl",
- "bucket",
- "cache-control",
- "content-disposition",
- "content-encoding",
- "content-type",
- "expires",
- "file",
- "key",
- "policy",
- "success_action_redirect",
- "success_action_status",
- "x-goog-algorithm",
- "x-goog-credential",
- "x-goog-date",
- "x-goog-signature");
-
- private static void validateFields(Map<String, String> fields) {
- for (String key : fields.keySet()) {
- if (!VALID_FIELDS.contains(key.toLowerCase())
- && !key.startsWith(Builder.CUSTOM_FIELD_PREFIX)) {
- throw new IllegalArgumentException("Invalid key: " + key);
- }
- }
- }
 
  private PostFieldsV4(Builder builder) {
  this(builder.fieldsMap);
  }
 
  private PostFieldsV4(Map<String, String> fields) {
- validateFields(fields);
  this.fieldsMap = Collections.unmodifiableMap(fields);
  }
 

google-cloud-storage/src/test/java/com/google/cloud/storage/PostPolicyV4Test.java

@@ -98,36 +98,12 @@ public void testPostPolicyV4_ofMalformedURL() {
  }
  }
 
- @Test
- public void testPostPolicyV4_ofInvalidField() {
- Map<String, String> fields = new HashMap<>(ALL_FIELDS);
- fields.put("$file", "file.txt");
- try {
- PostPolicyV4.of("http://google.com", fields);
- fail();
- } catch (IllegalArgumentException e) {
- assertEquals("Invalid key: $file", e.getMessage());
- }
- }
-
  @Test
  public void testPostFieldsV4_of() {
  PostPolicyV4.PostFieldsV4 fields = PostPolicyV4.PostFieldsV4.of(ALL_FIELDS);
  assertMapsEquals(ALL_FIELDS, fields.getFieldsMap());
  }
 
- @Test
- public void testPostFieldsV4_ofInvalidField() {
- Map<String, String> map = new HashMap<>();
- map.put("$file", "file.txt");
- try {
- PostPolicyV4.PostFieldsV4.of(map);
- fail();
- } catch (IllegalArgumentException e) {
- assertEquals("Invalid key: $file", e.getMessage());
- }
- }
-
  @Test
  public void testPostPolicyV4_builder() {
  PostPolicyV4.PostFieldsV4.Builder builder = PostPolicyV4.PostFieldsV4.newBuilder();