chore: fixed request and response

src/main/java/com/sendgrid/constant/ApplicationConstants.java

@@ -0,0 +1,7 @@
+package com.sendgrid.constant;
+
+import java.util.function.Predicate;
+
+public class ApplicationConstants {
+    public static final Predicate<Integer> SUCCESS = i -> i != null && i >= 200 && i < 400;
+}

src/main/java/com/sendgrid/http/ApiResponse.java

@@ -1,31 +1,27 @@
 package com.sendgrid.http;
 
 import lombok.Getter;
-
+import org.apache.http.Header;
 import java.util.Map;
 import java.util.StringJoiner;
 
 public class ApiResponse<T> {
     @Getter
     private Integer statusCode;
     @Getter
-    private String statusMessage;
-    @Getter
     private T body;
     @Getter
-    private Map<String, String> headers;
+    private Header[] headers;
 
 
-    public ApiResponse(int statusCode, String statusMessage, Map<String, String> headers) {
+    public ApiResponse(int statusCode, Header[] headers) {
         this.body = null;
         this.headers = headers;
         this.statusCode = statusCode;
-        this.statusMessage = statusMessage;
     }
 
-    public ApiResponse(int statusCode, String statusMessage, T body, Map<String, String> headers) {
+    public ApiResponse(int statusCode, T body, Header[] headers) {
         this.statusCode = statusCode;
-        this.statusMessage = statusMessage;
         this.body = body;
         this.headers = headers;
     }
@@ -34,9 +30,8 @@ public ApiResponse(int statusCode, String statusMessage, T body, Map<String, Str
     public String toString() {
         StringJoiner joiner = new StringJoiner(", ", ApiResponse.class.getSimpleName() + "(", ")");
         if (statusCode != null) joiner.add("statusCode=" + statusCode);
-        if (statusMessage != null) joiner.add("statusMessage=" + statusMessage);
-        if (statusMessage != null) joiner.add("body=" + body);
-        if (statusMessage != null) joiner.add("headers=" + headers);
+        if (headers != null) joiner.add("headers=" + headers);
+        if (body != null) joiner.add("body=" + body);
         return joiner.toString();
     }
 }

src/main/java/com/sendgrid/http/Request.java

@@ -60,7 +60,7 @@ public Builder addPathParam(String key, String value) {
             return this;
         }
 
-        public Builder addHeaderParams(String key, String value) {
+        public Builder addHeaderParam(String key, String value) {
             headers.put(key, value);
             return this;
         }
@@ -80,7 +80,7 @@ public Builder addQueryParams(String key, String value) {
             return this;
         }
 
-        public Builder body(String body) {
+        public Builder addBody(String body) {
             this.body = body;
             return this;
         }