diff --git a/.gitignore b/.gitignore
index b43d531..dfb17e1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -6,4 +6,5 @@ composer.phar
 /composer.lock
 /phpunit.xml
 /phpunit.phar
-/zoopla
\ No newline at end of file
+/zoopla
+.phpunit.cache
\ No newline at end of file
diff --git a/composer.json b/composer.json
index 7da2d91..a1cbe1b 100644
--- a/composer.json
+++ b/composer.json
@@ -13,11 +13,11 @@
         "php": ">=7.2",
         "ext-json": "*",
         "myclabs/php-enum": "1.*",
-        "guzzlehttp/guzzle": "^6.0.0",
+        "guzzlehttp/guzzle": "^6.0 || ^7.0",
         "justinrainbow/json-schema": "^5.2.10"
     },
     "require-dev": {
-        "phpunit/phpunit": "7.*"
+        "phpunit/phpunit": "9.*"
     },
     "autoload": {
         "psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 05337b0..023731a 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,28 +1,25 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit
-        bootstrap                   = "vendor/autoload.php"
-        colors                      = "true"
-        convertErrorsToExceptions   = "true"
-        convertNoticesToExceptions  = "true"
-        convertWarningsToExceptions = "true"
-        stopOnFailure               = "true">
-
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.6/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         cacheResultFile=".phpunit.cache/test-results"
+         executionOrder="depends,defects"
+         beStrictAboutOutputDuringTests="true"
+         beStrictAboutTodoAnnotatedTests="true"
+         convertDeprecationsToExceptions="true"
+         failOnRisky="true"
+         failOnWarning="true"
+         verbose="true">
     <testsuites>
-        <testsuite name="Zoopla Test">
-            <directory>./tests</directory>
+        <testsuite name="default">
+            <directory>tests</directory>
         </testsuite>
     </testsuites>
 
-    <filter>
-        <whitelist>
-            <directory>./src</directory>
-        </whitelist>
-    </filter>
-
-    <logging>
-        <log type="coverage-text" target="php://stdout" showUncoveredFiles="true"/>
-        <log type="coverage-html" target="build/logs/html"/>
-        <log type="coverage-clover" target="build/logs/clover.xml"/>
-        <log type="junit" target="build/logs/junit.xml" logIncompleteSkipped="false"/>
-    </logging>
-</phpunit>
\ No newline at end of file
+    <coverage cacheDirectory=".phpunit.cache/code-coverage"
+              processUncoveredFiles="true">
+        <include>
+            <directory suffix=".php">src</directory>
+        </include>
+    </coverage>
+</phpunit>
diff --git a/src/Groups/Area.php b/src/Groups/Area.php
index 2cbdcf9..8826018 100644
--- a/src/Groups/Area.php
+++ b/src/Groups/Area.php
@@ -5,7 +5,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\AreaUnit;
 
-class Area
+class Area implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Areas.php b/src/Groups/Areas.php
index 177fda6..599c97c 100644
--- a/src/Groups/Areas.php
+++ b/src/Groups/Areas.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class Areas
+class Areas implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Content.php b/src/Groups/Content.php
index 0ef77df..9239c9a 100644
--- a/src/Groups/Content.php
+++ b/src/Groups/Content.php
@@ -5,7 +5,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\ContentType;
 
-class Content
+class Content implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Coordinate.php b/src/Groups/Coordinate.php
index 84a58c7..3ddecb0 100644
--- a/src/Groups/Coordinate.php
+++ b/src/Groups/Coordinate.php
@@ -6,7 +6,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class Coordinate
+class Coordinate implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Description.php b/src/Groups/Description.php
index afab614..f23d24b 100644
--- a/src/Groups/Description.php
+++ b/src/Groups/Description.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class Description
+class Description implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Dimensions.php b/src/Groups/Dimensions.php
index 5a8633a..165bdda 100644
--- a/src/Groups/Dimensions.php
+++ b/src/Groups/Dimensions.php
@@ -5,7 +5,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\DimensionUnit;
 
-class Dimensions
+class Dimensions implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/EpcRating.php b/src/Groups/EpcRating.php
index 6b971aa..e613615 100644
--- a/src/Groups/EpcRating.php
+++ b/src/Groups/EpcRating.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class EpcRating
+class EpcRating implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/External.php b/src/Groups/External.php
index fafeeaa..462280b 100644
--- a/src/Groups/External.php
+++ b/src/Groups/External.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class External
+class External implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/GoogleStreetView.php b/src/Groups/GoogleStreetView.php
index 34de626..e5a5727 100644
--- a/src/Groups/GoogleStreetView.php
+++ b/src/Groups/GoogleStreetView.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class GoogleStreetView
+class GoogleStreetView implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/LeaseExpiry.php b/src/Groups/LeaseExpiry.php
index 927dcd9..29e6e5e 100644
--- a/src/Groups/LeaseExpiry.php
+++ b/src/Groups/LeaseExpiry.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class LeaseExpiry
+class LeaseExpiry implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Location.php b/src/Groups/Location.php
index 6082c6e..0bd8345 100644
--- a/src/Groups/Location.php
+++ b/src/Groups/Location.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class Location
+class Location implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/MinMaxArea.php b/src/Groups/MinMaxArea.php
index 0dfd161..bafb4b6 100644
--- a/src/Groups/MinMaxArea.php
+++ b/src/Groups/MinMaxArea.php
@@ -4,7 +4,7 @@
 
 use mehmetbulut\Zoopla\SynthesizeTrait;
 
-class MinMaxArea
+class MinMaxArea implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/MinimumContractLength.php b/src/Groups/MinimumContractLength.php
index cb625f9..01362f2 100644
--- a/src/Groups/MinimumContractLength.php
+++ b/src/Groups/MinimumContractLength.php
@@ -5,7 +5,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\RentalTermUnit;
 
-class MinimumContractLength
+class MinimumContractLength implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/PafAddress.php b/src/Groups/PafAddress.php
index 340d99f..be0b4b0 100644
--- a/src/Groups/PafAddress.php
+++ b/src/Groups/PafAddress.php
@@ -7,7 +7,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\PostCodeType;
 
-class PafAddress
+class PafAddress implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/PricePerUnitArea.php b/src/Groups/PricePerUnitArea.php
index 218be3f..a38999d 100644
--- a/src/Groups/PricePerUnitArea.php
+++ b/src/Groups/PricePerUnitArea.php
@@ -7,7 +7,7 @@
 use mehmetbulut\Zoopla\SynthesizeTrait;
 use mehmetbulut\Zoopla\Values\AreaUnit;
 
-class PricePerUnitArea
+class PricePerUnitArea implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/Pricing.php b/src/Groups/Pricing.php
index a70c893..38e8b6c 100644
--- a/src/Groups/Pricing.php
+++ b/src/Groups/Pricing.php
@@ -8,7 +8,7 @@
 use mehmetbulut\Zoopla\Values\PricingRentFrequency;
 use mehmetbulut\Zoopla\Values\TransactionType;
 
-class Pricing
+class Pricing implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/ServiceCharge.php b/src/Groups/ServiceCharge.php
index ebd022b..0947d23 100644
--- a/src/Groups/ServiceCharge.php
+++ b/src/Groups/ServiceCharge.php
@@ -6,7 +6,7 @@
 use mehmetbulut\Zoopla\Values\AreaUnit;
 use mehmetbulut\Zoopla\Values\Frequency;
 
-class ServiceCharge
+class ServiceCharge implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Groups/TenantEligibility.php b/src/Groups/TenantEligibility.php
index a64de0e..3e85b9a 100644
--- a/src/Groups/TenantEligibility.php
+++ b/src/Groups/TenantEligibility.php
@@ -6,7 +6,7 @@
 use mehmetbulut\Zoopla\Values\TenantEligibilityDss;
 use mehmetbulut\Zoopla\Values\TenantEligibilityStudent;
 
-class TenantEligibility
+class TenantEligibility implements \JsonSerializable
 {
 	use SynthesizeTrait;
 
diff --git a/src/Request/RequestBase.php b/src/Request/RequestBase.php
index ad9a36e..3b3d1ed 100755
--- a/src/Request/RequestBase.php
+++ b/src/Request/RequestBase.php
@@ -44,18 +44,6 @@ public function getObject()
 		return json_decode($this->getJson(), false);
 	}
 
-	public function jsonSerialize()
-	{
-		$data = [];
-		foreach ($this->arrSynthesize as $key => $value) {
-			if (isset($this->{$key}) && !empty($this->{$key})) {
-				$data[$key] = $this->{$key};
-			}
-		}
-
-		return $data;
-	}
-
 	public function getUrl($environment)
 	{
 		if ($environment == ZooplaRealTime::TEST) {
diff --git a/src/SynthesizeTrait.php b/src/SynthesizeTrait.php
index cb9b823..fd6b277 100644
--- a/src/SynthesizeTrait.php
+++ b/src/SynthesizeTrait.php
@@ -6,6 +6,8 @@
 
 trait SynthesizeTrait
 {
+	protected $_data = [];
+
 	public function __set($property, $value)
 	{
 		if ($this->hasProperty($property)) {
@@ -15,29 +17,28 @@ public function __set($property, $value)
 		}
 	}
 
+	public function __isset($property)
+	{
+		return isset($this->_data[$property]);
+	}
+
 	public function __get($property)
 	{
-		if (property_exists($this, $property)) {
-			return $this->{$property};
-		} else if ($this->hasProperty($property)) {
-			if (is_array($property)) {
-				return $this->{$property};
-			} else {
-				$class = $this->arrSynthesize[$property]['class'];
-				return $this->{$property} = new $class();
-			}
+		if (isset($this->_data[$property])) {
+			return $this->_data[$property];
 		}
 
-		throw new \Exception('Invalid param', Response::HTTP_BAD_REQUEST);
+		if (!$this->hasProperty($property)) {
+			throw new \Exception('Invalid param', Response::HTTP_BAD_REQUEST);
+		}
+
+		$class = $this->arrSynthesize[$property]['class'];
+		return $this->_data[$property] = new $class();
 	}
 
 	private function hasProperty($property): bool
 	{
-		if (isset($this->arrSynthesize[$property])) {
-			return true;
-		} else {
-			return false;
-		}
+		return isset($this->arrSynthesize[$property]);
 	}
 
 	private function setProperty($property, $value)
@@ -82,7 +83,7 @@ private function setProperty($property, $value)
 				if ($value) {
 					if (is_string($value)) {
 						$check = true;
-					} else if (is_object($value) && $value instanceof $param['class']) {
+					} else if ($value instanceof $param['class']) {
 						$check = true;
 					}
 				}
@@ -107,20 +108,29 @@ private function setProperty($property, $value)
 			case 'date'://Y-m-d
 				$format = 'Y-m-d';
 				$d = DateTime::createFromFormat($format, $value);
-				$check = $d && $d->format($format) == $value;
+				$check = $d && $d->format($format) === $value;
 				break;
 
 			case 'datetime'://Y-m-d H:i:s
 				$format = 'Y-m-d H:i:s';
 				$d = DateTime::createFromFormat($format, $value);
-				$check = $d && $d->format($format) == $value;
+				$check = $d && $d->format($format) === $value;
 				break;
 		}
 
 		if (!$check) {
 			throw new \Exception('Invalid type '.$property.' '.$param['type'], Response::HTTP_BAD_REQUEST);
-		} else if ($value) {
-			$this->{$property} = $value;
 		}
+
+		if (!$value) {
+			return;
+		}
+
+		$this->_data[$property] = $value;
+	}
+
+	public function jsonSerialize():array
+	{
+		return $this->_data;
 	}
 }
\ No newline at end of file
diff --git a/tests/SendPropertyTest.php b/tests/SendPropertyTest.php
index 4767082..ccd945a 100644
--- a/tests/SendPropertyTest.php
+++ b/tests/SendPropertyTest.php
@@ -123,7 +123,6 @@ public function testSendPropertyParams()
 		//location
 		$request->location->property_number_or_name = 'ds';
 		$request->location->street_name = 'ds';
-		$request->location->street_name = 'ds';
 		$request->location->locality = 'ds';
 		$request->location->town_or_city = 'ds';
 		$request->location->county = 'London';