Minor fixes (#902)

Author: ob-stripe

src/main/java/com/stripe/net/HttpContent.java

@@ -1,5 +1,7 @@
 package com.stripe.net;
 
+import static java.util.Objects.requireNonNull;
+
 import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.io.FileInputStream;
@@ -39,9 +41,7 @@ private HttpContent(byte[] byteArrayContent, String contentType) {
    */
   public static HttpContent buildFormURLEncodedContent(
       Collection<KeyValuePair<String, String>> nameValueCollection) throws IOException {
-    if (nameValueCollection == null) {
-      throw new IllegalArgumentException("nameValueCollection may not be null");
-    }
+    requireNonNull(nameValueCollection);
 
     return new HttpContent(
         FormEncoder.createQueryString(nameValueCollection).getBytes(ApiResource.CHARSET),
@@ -74,9 +74,7 @@ public static HttpContent buildMultipartFormDataContent(
   public static HttpContent buildMultipartFormDataContent(
       Collection<KeyValuePair<String, Object>> nameValueCollection, String boundary)
       throws IOException {
-    if (nameValueCollection == null) {
-      throw new IllegalArgumentException("nameValueCollection may not be null");
-    }
+    requireNonNull(nameValueCollection);
 
     ByteArrayOutputStream baos = new ByteArrayOutputStream();
     MultipartProcessor multipartProcessor = null;

src/test/java/com/stripe/net/HttpContentTest.java

@@ -2,7 +2,6 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertThrows;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.stripe.BaseStripeTest;
 import java.io.ByteArrayInputStream;
@@ -14,32 +13,30 @@
 
 public class HttpContentTest extends BaseStripeTest {
   @Test
-  public void TestBuildFormURLEncodedContentNull() throws IOException {
-    Throwable exception =
-        assertThrows(
-            IllegalArgumentException.class,
-            () -> {
-              HttpContent.buildFormURLEncodedContent(null);
-            });
-    assertTrue(exception.getMessage().contains("nameValueCollection may not be null"));
+  public void testBuildFormURLEncodedContentNull() throws IOException {
+    assertThrows(
+        NullPointerException.class,
+        () -> {
+          HttpContent.buildFormURLEncodedContent(null);
+        });
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentEmptySourceSuccess() throws IOException {
+  public void testBuildFormURLEncodedContentEmptySourceSuccess() throws IOException {
     HttpContent content =
         HttpContent.buildFormURLEncodedContent(new ArrayList<KeyValuePair<String, String>>());
     assertEquals(0, content.byteArrayContent().length);
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentEmptySourceCorrectContentType() throws IOException {
+  public void testBuildFormURLEncodedContentEmptySourceCorrectContentType() throws IOException {
     HttpContent content =
         HttpContent.buildFormURLEncodedContent(new ArrayList<KeyValuePair<String, String>>());
     assertEquals("application/x-www-form-urlencoded;charset=UTF-8", content.contentType());
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentOneEntrySeparatedByEquals() throws IOException {
+  public void testBuildFormURLEncodedContentOneEntrySeparatedByEquals() throws IOException {
     List<KeyValuePair<String, String>> data = new ArrayList<KeyValuePair<String, String>>();
     data.add(new KeyValuePair<String, String>("key", "value"));
 
@@ -49,7 +46,7 @@ public void TestBuildFormURLEncodedContentOneEntrySeparatedByEquals() throws IOE
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentOneUnicodeEntryEncoded() throws IOException {
+  public void testBuildFormURLEncodedContentOneUnicodeEntryEncoded() throws IOException {
     List<KeyValuePair<String, String>> data = new ArrayList<KeyValuePair<String, String>>();
     data.add(new KeyValuePair<String, String>("key", "valueク"));
 
@@ -60,7 +57,7 @@ public void TestBuildFormURLEncodedContentOneUnicodeEntryEncoded() throws IOExce
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentTwoEntriesSeparatedByAnd() throws IOException {
+  public void testBuildFormURLEncodedContentTwoEntriesSeparatedByAnd() throws IOException {
     List<KeyValuePair<String, String>> data = new ArrayList<KeyValuePair<String, String>>();
     data.add(new KeyValuePair<String, String>("key1", "value1"));
     data.add(new KeyValuePair<String, String>("key2", "value2"));
@@ -72,7 +69,7 @@ public void TestBuildFormURLEncodedContentTwoEntriesSeparatedByAnd() throws IOEx
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentWithSpacesEncodedAsPlus() throws IOException {
+  public void testBuildFormURLEncodedContentWithSpacesEncodedAsPlus() throws IOException {
     List<KeyValuePair<String, String>> data = new ArrayList<KeyValuePair<String, String>>();
     data.add(new KeyValuePair<String, String>("key 1", "val%20ue 1"));
     data.add(new KeyValuePair<String, String>("key 2", "val%ue 2"));
@@ -85,7 +82,7 @@ public void TestBuildFormURLEncodedContentWithSpacesEncodedAsPlus() throws IOExc
   }
 
   @Test
-  public void TestBuildFormURLEncodedContentWithSquareBracketsUnencoded() throws IOException {
+  public void testBuildFormURLEncodedContentWithSquareBracketsUnencoded() throws IOException {
     List<KeyValuePair<String, String>> data = new ArrayList<KeyValuePair<String, String>>();
     data.add(new KeyValuePair<String, String>("key[subkey]", "[#value]"));
 
@@ -96,18 +93,16 @@ public void TestBuildFormURLEncodedContentWithSquareBracketsUnencoded() throws I
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNull() throws IOException {
-    Throwable exception =
-        assertThrows(
-            IllegalArgumentException.class,
-            () -> {
-              HttpContent.buildMultipartFormDataContent(null);
-            });
-    assertTrue(exception.getMessage().contains("nameValueCollection may not be null"));
+  public void testBuildMultipartFormDataContentNull() throws IOException {
+    assertThrows(
+        NullPointerException.class,
+        () -> {
+          HttpContent.buildMultipartFormDataContent(null);
+        });
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNullEmptySourceCorrectContentType()
+  public void testBuildMultipartFormDataContentNullEmptySourceCorrectContentType()
       throws IOException {
     HttpContent content =
         HttpContent.buildMultipartFormDataContent(
@@ -116,7 +111,7 @@ public void TestBuildMultipartFormDataContentNullEmptySourceCorrectContentType()
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNullEmptySourceSuccess() throws IOException {
+  public void testBuildMultipartFormDataContentNullEmptySourceSuccess() throws IOException {
     List<KeyValuePair<String, Object>> data = new ArrayList<KeyValuePair<String, Object>>();
 
     HttpContent content = HttpContent.buildMultipartFormDataContent(data, "test-boundary");
@@ -126,7 +121,7 @@ public void TestBuildMultipartFormDataContentNullEmptySourceSuccess() throws IOE
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNullOneStringEntrySuccess() throws IOException {
+  public void testBuildMultipartFormDataContentNullOneStringEntrySuccess() throws IOException {
     List<KeyValuePair<String, Object>> data = new ArrayList<KeyValuePair<String, Object>>();
     data.add(new KeyValuePair<String, Object>("key", "valueク"));
 
@@ -139,7 +134,7 @@ public void TestBuildMultipartFormDataContentNullOneStringEntrySuccess() throws
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNullOneStreamEntrySuccess() throws IOException {
+  public void testBuildMultipartFormDataContentNullOneStreamEntrySuccess() throws IOException {
     List<KeyValuePair<String, Object>> data = new ArrayList<KeyValuePair<String, Object>>();
     data.add(
         new KeyValuePair<String, Object>(
@@ -155,7 +150,7 @@ public void TestBuildMultipartFormDataContentNullOneStreamEntrySuccess() throws
   }
 
   @Test
-  public void TestBuildMultipartFormDataContentNullTwoEntriesSuccess() throws IOException {
+  public void testBuildMultipartFormDataContentNullTwoEntriesSuccess() throws IOException {
     List<KeyValuePair<String, Object>> data = new ArrayList<KeyValuePair<String, Object>>();
     data.add(
         new KeyValuePair<String, Object>(