spotbugs plugin docs (#172)

Co-authored-by: Radai Rosenblatt <[email protected]>

spotbugs-plugin/README.md

@@ -0,0 +1,61 @@
+# Spotbugs-Plugin
+
+this module holds a plugin containing [spotbugs](https://spotbugs.github.io/) rules for finding usage of incompatible avro APIs in java code.
+
+## how to use
+
+### gradle projects
+
+(for a complete example see te spotbugs demo)
+
+1st make sure your project is using the [spotbugs gradle plugin](https://plugins.gradle.org/plugin/com.github.spotbugs):
+```
+plugins {
+  id "com.github.spotbugs" version "<latest spotbugs-gradle-plugin>"
+}
+```
+then configure both the version of spotbugs itself and add this plugin via dependencies:
+```
+dependencies {
+  spotbugs "com.github.spotbugs:spotbugs:<latest spotbugs>"
+  spotbugsPlugins "com.linkedin.avroutil1.spotbugs-plugin:<latest avro-util>"        
+}
+```
+for further details on how to customize includes/excludes and reporting, see [spotbugs-gradle-plugin docs](https://github.com/spotbugs/spotbugs-gradle-plugin)
+
+### command line
+
+(for complete docs see [relevant section of the spotbugs docs](https://spotbugs.readthedocs.io/en/stable/running.html))
+
+```
+java -jar spotbugs.jar -pluginList spotbugs-plugin.jar ...
+```
+## table of incompatible APIs and their helper replacements
+
+| code | rule | incompatible code | compatible replacement |
+|------|------|-------------------|------------------------|
+| BDI  | BinaryDecoder instantiation | ```new BinaryDecoder(...)```  | ```AvroCompatibilityHelper.newBinaryDecoder(...)``` |
+| BEI  | BinaryEncoder instantiation | ```new BinaryEncoder(...)```  | ```AvroCompatibilityHelper.newBinaryEncoder(...)``` |
+| ESI  | EnumSymbol instantiation    | ```new EnumSymbol(...)```     | ```AvroCompatibilityHelper.newEnumSymbol(...)``` |
+| FDVA | Field default value access  | ```field.defaultVelue()```    | ```AvroCompatibilityHelper.get<Generic\|Specific>DefaultValue(...)``` |
+|      |                             | ```field.defaultVel()```      | ```AvroCompatibilityHelper.get<Generic\|Specific>DefaultValue(...)``` |
+| FI   | Fixed Instantiation         | ```new Fixed(...)```          | ```AvroCompatibilityHelper.newFixed(...)``` |
+| IOGR | instanceof GenericRecord    | ```x instanceof GenericRecord``` | ```AvroCompatibilityHelper.isGenericRecord(...)``` |
+| JDI  | JsonDecoder instantiation   | ```new JsonDecoder(...)``` | ```AvroCompatibilityHelper.new<Compatible>JsonDecoder(...)``` |
+| JDFI |                             | ```DecoderFactory.jsonDecoder(...)``` | ```AvroCompatibilityHelper.new<Compatible>JsonDecoder(...)``` |
+| JEI  | JsonEncoder instantiation   | ```new JsonEncoder(...)``` | ```AvroCompatibilityHelper.newJsonEncoder(...)``` |
+| OSCI | SchemaConstructable usage   | ```implements SchemaConstructable``` | avoid |
+|      | SchemaConstructable instantiation | part of decoding | ```AvroCompatibilityHelper.newInstance(...)``` |
+| PA   | Schema/Field prop access    | ```x.getJsonProp()``` | ```AvroCompatibilityHelper.get<Field\|Schema>PropAsJsonString(...)``` |
+|      |                             | ```x.getObjectProp()``` | ```AvroCompatibilityHelper.get<Field\|Schema>PropAsJsonString(...)``` |
+|      |                             | ```x.props()``` | ```AvroCompatibilityHelper.get<Field\|Schema>PropAsJsonString(...)``` |
+|      |                             | ```x.getJsonProps()``` | ```AvroCompatibilityHelper.get<Field\|Schema>PropAsJsonString(...)``` |
+|      |                             | ```x.getObjectProps()``` | ```AvroCompatibilityHelper.get<Field\|Schema>PropAsJsonString(...)``` |
+|      |                             | ```x.addProp(<JsonNode\|Object>)``` | ```AvroCompatibilityHelper.cloneSchema(...) or AvroCompatibilityHelper.createSchemaField(...)``` |
+|      |                             | ```x.addAllProps(...)``` | ```AvroCompatibilityHelper.cloneSchema(...) or AvroCompatibilityHelper.createSchemaField(...)``` |
+| SFI  | Schema.Field instantiation  | ```new Schema.Field(...)``` | ```AvroCompatibilityHelper.createSchemaField(...)``` |
+| SDNI | SpecificData.newInstance()  | ```SpecificData.newInstance(...)``` | ```AvroCompatibilityHelper.newInstance(...)``` |
+
+## incompatible APIs in detail
+
+TBD

spotbugs-plugin/src/main/resources/messages.xml

@@ -290,6 +290,7 @@
     <BugCode abbrev="BDI">BinaryDecoder instantiation</BugCode>
     <BugCode abbrev="BEI">BinaryEncoder instantiation</BugCode>
     <BugCode abbrev="ESI">EnumSymbol instantiation</BugCode>
+    <BugCode abbrev="FDVA">Field default value access</BugCode>
     <BugCode abbrev="FI">Fixed instantiation</BugCode>
     <BugCode abbrev="IOGR">instanceof GenericRecord</BugCode>
     <BugCode abbrev="JDI">JsonDecoder instantiation</BugCode>