PATCH request failed for CRM REST API

I am updating the case record partially through CRM API with PATCH request. While doing in postman, its successfully updated. But from the code, I am getting exception as below.

"exceptionStacktrace": "java.lang.RuntimeException: java.lang.RuntimeException: java.net.ProtocolException: Invalid HTTP method: PATCH\n\tat com.spr.crm.apiClient.dynamics.DynamicsApiClientImpl.updateEntity(DynamicsApiClientImpl.java:111)\n\tat com.spr.crm.handler.clients.DynamicsCRMClient.updateDynamicsCase(DynamicsCRMClient.java:560)\n\tat com.spr.crm.handler.clients.DynamicsCRMClient.handleCaseUpdated(DynamicsCRMClient.java:112)\n\tat com.spr.common.WebhookType$2.handleWebhook(WebhookType.java:62)\n\tat com.spr.crm.handler.CrmSinkHandlerImpl.handle(CrmSinkHandlerImpl.java:41)\n\tat com.spr.crm.executor.tasks.CrmWebhookTask.doRun(CrmWebhookTask.java:37)\n\tat com.spr.common.tasks.AbstractTask.run(AbstractTask.java:73)\n\tat com.spr.executor.CommonPartitionedTaskExecutor.lambda$initializeConsumer$0(CommonPartitionedTaskExecutor.java:91)\n\tat java.lang.Thread.run(Thread.java:748)\nCaused by: java.lang.RuntimeException: java.net.ProtocolException: Invalid HTTP method: PATCH\n\tat com.spr.crm.apiClient.dynamics.DynamicsApiClientImpl.makeCall(DynamicsApiClientImpl.java:150)\n\tat com.spr.crm.apiClient.dynamics.DynamicsApiClientImpl.updateEntity(DynamicsApiClientImpl.java:104)\n\t... 8 more\nCaused by: java.net.ProtocolException: Invalid HTTP method: PATCH\n\tat java.net.HttpURLConnection.setRequestMethod(HttpURLConnection.java:440)\n\tat sun.net.www.protocol.http.HttpURLConnection.setRequestMethod(HttpURLConnection.java:553)\n\tat sun.net.www.protocol.https.HttpsURLConnectionImpl.setRequestMethod(HttpsURLConnectionImpl.java:388)\n\tat com.spr.crm.apiClient.http.HttpExecutorImpl.doRequest(HttpExecutorImpl.java:215)\n\tat com.spr.crm.apiClient.http.HttpExecutorImpl.requestViaProxyIncludeHeaders(HttpExecutorImpl.java:114)\n\tat com.spr.crm.apiClient.dynamics.DynamicsApiClientImpl.lambda$updateEntity$2(DynamicsApiClientImpl.java:105)\n\tat com.spr.crm.apiClient.dynamics.DynamicsApiClientImpl.makeCall(DynamicsApiClientImpl.java:147)\n\t... 9 more\n"