improve errors processing

indexer-core/src/main/java/org/opengroup/osdu/indexer/schema/converter/tech.md

+## Table of contests.
+
+1.  Purpose
+
+2.  Package details and main classes
+
+3.  Unit tests
+
+4.  Troubleshooting
+
+5.  Schema retrieval order
+    
+6.  Converter extensions/modifications
+
+#### Purpose
+The purpose of this document is to provide overview of the Schema
+converter from the technical point of view. If you need to know more
+about transformations, conversion rules, please see
+<https://community.opengroup.org/osdu/platform/system/indexer-service/-/blob/master/indexer-core/src/main/java/org/opengroup/osdu/indexer/schema/converter/readme.md>
+
+#### Package details and main classes
+Schema converter is in org.opengroup.osdu.indexer.schema.converter
+package.
+
+<table>
+<thead>
+<tr class="header">
+<th>Name</th>
+<th>Description</th>
+<th>Type</th>
+</tr>
+</thead>
+<tbody>
+<tr class="odd">
+<td>config</td>
+<td>Contains configuration classes, configuration can be changed via properties file</td>
+<td>package</td>
+</tr>
+<tr class="even">
+<td>exception</td>
+<td>Processing exceptions</td>
+<td>package</td>
+</tr>
+<tr class="odd">
+<td>Interfaces/ SchemaToStorageFormat.java</td>
+<td><p>Interface that provides</p>
+<p>convertToString(String schemaServiceFormat, String kind); method</p></td>
+<td>file</td>
+</tr>
+<tr class="even">
+<td>tags</td>
+<td>Supported tags</td>
+<td>package</td>
+</tr>
+<tr class="odd">
+<td>PropertiesProcessor.java</td>
+<td>Recursively processes items</td>
+<td>file</td>
+</tr>
+<tr class="even">
+<td>SchemaToStorageFormatImpl.java</td>
+<td>Parse json, calls PropertiesProcessor</td>
+<td>file</td>
+</tr>
+<tr class="odd">
+<td>Readme.md</td>
+<td></td>
+<td>file</td>
+</tr>
+</tbody>
+</table>
+
+Package members.
+
+#### Unit tests
+
+If you have any issues with schema (loading, conversion, etc.) you can
+easily create a unit test that checks a schema in
+SchemaToStorageFormatImplTest class.
+
+For instance
+```json
+@Test(expected = SchemaProcessingException.**class**)  
+public void wrongDefinitions() {  
+testSingleFile("/converter/bad-schema/wrong-definitions-and-missed-type.json"**,
+KIND);  
+}
+```
+Expects that schema is wrong
+
+testSingleFile loads a schema, tries to convert it, then compares it
+with expected storage schema that is loaded from &lt;filename&gt; +
+“.res” file.
+
+Pay attention to folderPassed() method it recursively processes a set of
+schemas in a folder.
+
+#### Troubleshooting.
+
+The latest schema converter tries to gather as much conversion errors as
+possible (the more the better). Please see logs if conversion not
+happens.
+
+If a processing of some schema generates unexpected errors take that
+schema and investigate with unit test as was described before.
+
+#### Schema retrieval order.
+
+Schema is retrieved from the Schema service first. If schema is not
+found in the Schema Service it is retrieved from the Storage Service. If
+schema is found in the Schema Service but conversion failed for some
+reason the schema is not retrieved from the Storage Service. Please see
+org.opengroup.osdu.indexer.service.impl.SchemaProviderImpl for details
+
+#### Converter extensions/modifications
+
+a) Add new tags to schema.converter.tags package
+
+b) Modify PropertiesProcessor
+
+c) Add/change unit and integration tests
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