### Question:
JaxRsRequest extends RequestDetails { @Override public String getHeader(String headerKey) { List<String> requestHeader = getHeaders(headerKey); return requestHeader.isEmpty() ? null : requestHeader.get(0); } JaxRsRequest(AbstractJaxRsProvider server, String resourceString, RequestTypeEnum requestType,
							  RestOperationTypeEnum restOperation); @Override Charset getCharset(); @Override FhirContext getFhirContext(); @Override String getHeader(String headerKey); @Override List<String> getHeaders(String name); @Override Object getAttribute(String theAttributeName); @Override void setAttribute(String theAttributeName, Object theAttributeValue); @Override InputStream getInputStream(); @Override Reader getReader(); @Override IRestfulResponse getResponse(); @Override AbstractJaxRsProvider getServer(); void setServer(AbstractJaxRsProvider theServer); @Override String getServerBaseForRequest();  }### Answer:
@Test public void testGetHeader() { String headerKey = "key"; String headerValue = "location_value"; String headerValue2 = "location_value_2"; assertTrue(StringUtils.isBlank(details.getHeader(headerKey))); queryParameters.add(headerKey, headerValue); assertEquals(headerValue, details.getHeader(headerKey)); assertEquals(Arrays.asList(headerValue), details.getHeaders(headerKey)); queryParameters.add(headerKey, headerValue2); assertEquals(headerValue, details.getHeader(headerKey)); assertEquals(Arrays.asList(headerValue, headerValue2), details.getHeaders(headerKey)); }