diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BasicBillingPlan.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BasicBillingPlan.java
new file mode 100644
index 00000000..6a5d0341
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BasicBillingPlan.java
@@ -0,0 +1,4 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class BasicBillingPlan extends BillingPlan {
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BillingPlan.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BillingPlan.java
new file mode 100644
index 00000000..d4651641
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/BillingPlan.java
@@ -0,0 +1,4 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class BillingPlan {
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Customer.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Customer.java
new file mode 100644
index 00000000..e0c08184
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Customer.java
@@ -0,0 +1,44 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class Customer {
+
+    private String name;
+
+    private BillingPlan billingPlan;
+
+    private PaymentHistory paymentHistory;
+
+    public Customer(String name, BillingPlan billingPlan, PaymentHistory paymentHistory) {
+        this.name = name;
+        this.billingPlan = billingPlan;
+        this.paymentHistory = paymentHistory;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public BillingPlan getBillingPlan() {
+        return billingPlan;
+    }
+
+    public void setBillingPlan(BillingPlan billingPlan) {
+        this.billingPlan = billingPlan;
+    }
+
+    public PaymentHistory getPaymentHistory() {
+        return paymentHistory;
+    }
+
+    public void setPaymentHistory(PaymentHistory paymentHistory) {
+        this.paymentHistory = paymentHistory;
+    }
+
+    public boolean isUnknown() {
+        return false;
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerService.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerService.java
new file mode 100644
index 00000000..84e3e65a
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerService.java
@@ -0,0 +1,17 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class CustomerService {
+
+    public String customerName(Site site) {
+        return site.getCustomer().getName();
+    }
+
+    public BillingPlan billingPlan(Site site) {
+       return site.getCustomer().getBillingPlan();
+    }
+
+    public int weeksDelinquent(Site site) {
+        return site.getCustomer().getPaymentHistory().getWeeksDelinquentInLastYear();
+    }
+
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/NullPaymentHistory.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/NullPaymentHistory.java
new file mode 100644
index 00000000..ca0bb9ce
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/NullPaymentHistory.java
@@ -0,0 +1,7 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class NullPaymentHistory extends PaymentHistory {
+    public NullPaymentHistory() {
+        super(0);
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/PaymentHistory.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/PaymentHistory.java
new file mode 100644
index 00000000..636802d4
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/PaymentHistory.java
@@ -0,0 +1,14 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class PaymentHistory {
+
+    private int weeksDelinquentInLastYear;
+
+    public PaymentHistory(int weeksDelinquentInLastYear) {
+        this.weeksDelinquentInLastYear = weeksDelinquentInLastYear;
+    }
+
+    public int getWeeksDelinquentInLastYear() {
+        return this.weeksDelinquentInLastYear;
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Site.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Site.java
new file mode 100644
index 00000000..adda8f1b
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/Site.java
@@ -0,0 +1,14 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class Site {
+
+    private Customer customer;
+
+    public Site(Customer customer) {
+        this.customer = customer.getName().equals("unknown") ? new UnknownCustomer() : customer;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/UnknownCustomer.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/UnknownCustomer.java
new file mode 100644
index 00000000..9245b87a
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/UnknownCustomer.java
@@ -0,0 +1,18 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+public class UnknownCustomer extends Customer {
+
+    public UnknownCustomer() {
+        super("unknown", new BasicBillingPlan(), new NullPaymentHistory());
+    }
+
+    @Override
+    public boolean isUnknown() {
+        return true;
+    }
+
+    @Override
+    public String getName() {
+        return "occupant";
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BasicBillingPlan.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BasicBillingPlan.java
new file mode 100644
index 00000000..786f1ead
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BasicBillingPlan.java
@@ -0,0 +1,4 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class BasicBillingPlan extends BillingPlan {
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BillingPlan.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BillingPlan.java
new file mode 100644
index 00000000..3c2873ed
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/BillingPlan.java
@@ -0,0 +1,4 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class BillingPlan {
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Customer.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Customer.java
new file mode 100644
index 00000000..1308df1e
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Customer.java
@@ -0,0 +1,40 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class Customer {
+
+    private String name;
+
+    private BillingPlan billingPlan;
+
+    private PaymentHistory paymentHistory;
+
+    public Customer(String name, BillingPlan billingPlan, PaymentHistory paymentHistory) {
+        this.name = name;
+        this.billingPlan = billingPlan;
+        this.paymentHistory = paymentHistory;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public BillingPlan getBillingPlan() {
+        return billingPlan;
+    }
+
+    public void setBillingPlan(BillingPlan billingPlan) {
+        this.billingPlan = billingPlan;
+    }
+
+    public PaymentHistory getPaymentHistory() {
+        return paymentHistory;
+    }
+
+    public void setPaymentHistory(PaymentHistory paymentHistory) {
+        this.paymentHistory = paymentHistory;
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/CustomerService.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/CustomerService.java
new file mode 100644
index 00000000..58690c33
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/CustomerService.java
@@ -0,0 +1,28 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class CustomerService {
+
+    public String customerName(Site site) {
+        Customer customer = site.getCustomer();
+
+        String customerName;
+        if (customer.getName().equals("unknown")) {
+            customerName = "occupant";
+        } else {
+            customerName = customer.getName();
+        }
+
+        return customerName;
+    }
+
+    public BillingPlan billingPlan(Site site) {
+        Customer customer = site.getCustomer();
+        return customer.getName().equals("unknown") ? new BasicBillingPlan() : customer.getBillingPlan();
+    }
+
+    public int weeksDelinquent(Site site) {
+        Customer customer = site.getCustomer();
+        return customer.getName().equals("unknown") ? 0 : customer.getPaymentHistory().getWeeksDelinquentInLastYear();
+    }
+
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/PaymentHistory.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/PaymentHistory.java
new file mode 100644
index 00000000..7df0608e
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/PaymentHistory.java
@@ -0,0 +1,14 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class PaymentHistory {
+
+    private int weeksDelinquentInLastYear;
+
+    public PaymentHistory(int weeksDelinquentInLastYear) {
+        this.weeksDelinquentInLastYear = weeksDelinquentInLastYear;
+    }
+
+    public int getWeeksDelinquentInLastYear() {
+        return this.weeksDelinquentInLastYear;
+    }
+}
diff --git a/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Site.java b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Site.java
new file mode 100644
index 00000000..f6da0d9b
--- /dev/null
+++ b/refactoring/src/main/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/_before/Site.java
@@ -0,0 +1,14 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case._before;
+
+public class Site {
+
+    private Customer customer;
+
+    public Site(Customer customer) {
+        this.customer = customer;
+    }
+
+    public Customer getCustomer() {
+        return customer;
+    }
+}
diff --git a/refactoring/src/test/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerServiceTest.java b/refactoring/src/test/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerServiceTest.java
new file mode 100644
index 00000000..85147ae1
--- /dev/null
+++ b/refactoring/src/test/java/com/example/refactoring/_16_temporary_field/_36_introduce_special_case/CustomerServiceTest.java
@@ -0,0 +1,39 @@
+package com.example.refactoring._16_temporary_field._36_introduce_special_case;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CustomerServiceTest {
+
+    CustomerService customerService = new CustomerService();
+    Customer unknown = new Customer("unknown", null, null);
+
+    BillingPlan billingPlan = new BillingPlan();
+    Customer kim = new Customer("kim", billingPlan, new PaymentHistory(1));
+
+    @Test
+    void customerName() {
+        String unknownCustomerName = customerService.customerName(new Site(unknown));
+        assertEquals("occupant", unknownCustomerName);
+
+        String customer = customerService.customerName(new Site(kim));
+        assertEquals("kim", customer);
+    }
+
+    @Test
+    void billingPlan() {
+        assertTrue((customerService.billingPlan(new Site(unknown)) instanceof BasicBillingPlan));
+
+        assertEquals(billingPlan, customerService.billingPlan(new Site(kim)));
+    }
+
+    @Test
+    void weeksDelingquent() {
+        assertEquals(1, customerService.weeksDelinquent(new Site(kim)));
+
+        assertEquals(0, customerService.weeksDelinquent(new Site(unknown)));
+    }
+
+
+}
\ No newline at end of file