Exception on null or invalid date format when searching

[aaronforshaw]

Description

Following the fix for #321, a null pointer exception is provoked by posting a null date value. e.g.

POST /api/catalogueItems/search
with body

{"searchTerm":"CDW","limit":50,"offset":0,"domainTypes":[],"labelOnly":false,"dataModelTypes":null,"lastUpdatedAfter":null,"lastUpdatedBefore":null,"createdAfter":null,"createdBefore":null,"pageSize":50,"pageIndex":0}

A ParseException is provoked by sending an string which cannot be parsed to a date.

Steps to reproduce

The former can be reproduced by using the UI search function with no dates set (in which case the UI sends null values for each date field).

The latter can be provoked by constructing an unparsable string in Postman.

Expected behaviour

The endpoint should tolerate null or malformed date strings.

Screenshots

type: "NullPointerException"
message: "Cannot invoke "String.length()" because "text" is null"
stacktrace:
0: "java.text.SimpleDateFormat.parse(SimpleDateFormat.java:1474)"
1: "java.text.DateFormat.parse(DateFormat.java:397)"
2: "uk.ac.ox.softeng.maurodatamapper.core.rest.transport.search.SearchParams.bindDate(SearchParams.groovy:134)"
3: "uk.ac.ox.softeng.maurodatamapper.core.rest.transport.search.SearchParams.setLastUpdatedAfter(SearchParams.groovy:92)"
4: "jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)"
5: "jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)"
6: "uk.ac.ox.softeng.maurodatamapper.core.rest.transport.search.SearchParams$_bind_closure1.doCall(SearchParams.groovy:116)"
7: "jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)"
8: "jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)"
9: "uk.ac.ox.softeng.maurodatamapper.core.rest.transport.search.SearchParams.bind(SearchParams.groovy:115)"
10: "uk.ac.ox.softeng.maurodatamapper.datamodel.DataModelController.search(DataModelController.groovy:87)"
11: "jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)"
12: "jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)"
13: "org.grails.core.DefaultGrailsControllerClass$ReflectionInvoker.invoke(DefaultGrailsControllerClass.java:211)"
14: "org.grails.core.DefaultGrailsControllerClass.invoke(DefaultGrailsControllerClass.java:188)"
15: "org.grails.web.mapping.mvc.UrlMappingsInfoHandlerAdapter.handle(UrlMappingsInfoHandlerAdapter.groovy:90)"
16: "org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1067)"
17: "org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:963)"
18: "org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)"
19: "org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)"
20: "org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)"
21: "org.grails.web.servlet.mvc.GrailsWebRequestFilter.doFilterInternal(GrailsWebRequestFilter.java:77)"
22: "org.grails.web.filters.HiddenHttpMethodFilter.doFi

Environment

develop branch of mdm-core