Could not read JSON Can not deserialize instance of demo.

org.springframework.http.converter.HttpMessageNotReadableException: Could not read JSON: Can not deserialize instance of demo.integration.dto.PurchaseOrderResource out of START_ARRAY token
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@2864f887; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of demo.integration.dto.PurchaseOrderResource out of START_ARRAY token
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@2864f887; line: 1, column: 1]
	at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:228)
	at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.read(MappingJackson2HttpMessageConverter.java:220)
	at org.springframework.web.client.HttpMessageConverterExtractor.extractData(HttpMessageConverterExtractor.java:95)
	at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:795)
	at org.springframework.web.client.RestTemplate$ResponseEntityResponseExtractor.extractData(RestTemplate.java:779)
	at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:559)
	at org.springframework.web.client.RestTemplate.execute(RestTemplate.java:512)
	at org.springframework.web.client.RestTemplate.postForEntity(RestTemplate.java:363)
	at demo.services.rentit.RentalService.createPurchaseOrder(RentalService.java:113)
	at demo.services.rentit.APIMockRentItServiceUnitTest.testApprovePHRCreatePurchaseOrder(APIMockRentItServiceUnitTest.java:178)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
	at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:74)
	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:83)
	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:72)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:233)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:87)
	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:71)
	at org.junit.runners.ParentRunner.run(ParentRunner.java:309)
	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:176)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
	at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:675)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)
Caused by: com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of demo.integration.dto.PurchaseOrderResource out of START_ARRAY token
 at [Source: sun.net.www.protocol.http.HttpURLConnection$HttpInputStream@2864f887; line: 1, column: 1]
	at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164)
	at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:691)
	at com.fasterxml.jackson.databind.DeserializationContext.mappingException(DeserializationContext.java:685)
	at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromArray(BeanDeserializerBase.java:1215)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer._deserializeOther(BeanDeserializer.java:151)
	at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:126)
	at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:2993)
	at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2158)
	at org.springframework.http.converter.json.MappingJackson2HttpMessageConverter.readJavaType(MappingJackson2HttpMessageConverter.java:225)
	... 38 more