Make tests more stable by using JSONAssert equals (#6247)

`avroSchema.getSchemaInfo().getSchema()`  in `src/test/java/org/apache/pulsar/client/impl/schema/AvroSchemaTest.java` returns a JSON object. `schemaJson` compares with hard-coded JSON String. However, the order of entries in `schemaJson` is not guaranteed so the json results can contain entries in any order.

This PR proposes to use JSONAssert and modify the corresponding json test assertions so that the test is more stable.

### Motivation

Using JSONAssert and modifying the corresponding json test assertions so that the test is more stable.

### Modifications

Adding `assertJSONEquals` method and replacing `assertEquals` with it in tests `testNotAllowNullSchema` and `testAllowNullSchema`.

pom.xml

@@ -215,6 +215,7 @@ flexible messaging model and an intuitive client API.</description>
     <powermock.version>2.0.2</powermock.version>
     <javassist.version>3.25.0-GA</javassist.version>
     <failsafe.version>2.3.1</failsafe.version>
+    <skyscreamer.version>1.5.0</skyscreamer.version>
 
     <!-- Plugin dependencies -->
     <protobuf-maven-plugin.version>0.6.1</protobuf-maven-plugin.version>

pulsar-client/pom.xml

@@ -151,6 +151,13 @@
       <version>${project.parent.version}</version>
       <scope>test</scope>
     </dependency>
+
+    <dependency>
+      <groupId>org.skyscreamer</groupId>
+      <artifactId>jsonassert</artifactId>
+      <version>${skyscreamer.version}</version>
+      <scope>test</scope>
+    </dependency> 
   </dependencies>
 
   <build>

pulsar-client/src/test/java/org/apache/pulsar/client/impl/schema/AvroSchemaTest.java

@@ -53,6 +53,8 @@
 import org.apache.pulsar.client.impl.schema.SchemaTestUtils.Foo;
 import org.apache.pulsar.common.schema.SchemaInfo;
 import org.apache.pulsar.common.schema.SchemaType;
+import org.json.JSONException;
+import org.skyscreamer.jsonassert.JSONAssert;
 import org.testng.Assert;
 import org.testng.annotations.Test;
 
@@ -142,13 +144,17 @@ public void testSchemaDefinition() throws SchemaValidationException {
         }
     }
 
+    public void assertJSONEquals(String s1, String s2) throws JSONException {
+        JSONAssert.assertEquals(s1, s2, false);
+    }
+
     @Test
-    public void testNotAllowNullSchema() {
+    public void testNotAllowNullSchema() throws JSONException {
         AvroSchema<Foo> avroSchema = AvroSchema.of(SchemaDefinition.<Foo>builder().withPojo(Foo.class).withAlwaysAllowNull(false).build());
         assertEquals(avroSchema.getSchemaInfo().getType(), SchemaType.AVRO);
         Schema.Parser parser = new Schema.Parser();
         String schemaJson = new String(avroSchema.getSchemaInfo().getSchema());
-        assertEquals(schemaJson, SCHEMA_AVRO_NOT_ALLOW_NULL);
+        assertJSONEquals(schemaJson, SCHEMA_AVRO_NOT_ALLOW_NULL);
         Schema schema = parser.parse(schemaJson);
 
         for (String fieldName : FOO_FIELDS) {
@@ -165,13 +171,13 @@ public void testNotAllowNullSchema() {
     }
 
     @Test
-    public void testAllowNullSchema() {
+    public void testAllowNullSchema() throws JSONException {
         AvroSchema<Foo> avroSchema = AvroSchema.of(SchemaDefinition.<Foo>builder().withPojo(Foo.class).build());
         assertEquals(avroSchema.getSchemaInfo().getType(), SchemaType.AVRO);
         Schema.Parser parser = new Schema.Parser();
         parser.setValidateDefaults(false);
         String schemaJson = new String(avroSchema.getSchemaInfo().getSchema());
-        assertEquals(schemaJson, SCHEMA_AVRO_ALLOW_NULL);
+        assertJSONEquals(schemaJson, SCHEMA_AVRO_ALLOW_NULL);
         Schema schema = parser.parse(schemaJson);
 
         for (String fieldName : FOO_FIELDS) {