add java directive to security insight (Azure#17295)

Author: XiaofeiCao

specification/securityinsights/resource-manager/readme.java.md

@@ -0,0 +1,16 @@
+## Java
+
+These settings apply only when `--java` is specified on the command line.
+
+
+``` yaml $(java)
+directive:
+  - from: ThreatIntelligence.json
+    where: $.definitions.ThreatIntelligenceInformation.allOf[1]
+    set:
+      type: object
+    reason: discriminator property is required to be defined in the model
+  - from: ThreatIntelligence.json
+    where: $.definitions
+    transform: $.ThreatIntelligenceInformation.properties = $.ThreatIntelligenceResourceKind.properties
+```

specification/securityinsights/resource-manager/readme.md

@@ -154,6 +154,7 @@ swagger-to-sdk:
   - repo: azure-sdk-for-python-track2
   - repo: azure-sdk-for-js
   - repo: azure-sdk-for-node
+  - repo: azure-sdk-for-java
   - repo: azure-cli-extensions
   - repo: azure-resource-manager-schemas
 ```
@@ -188,3 +189,7 @@ See configuration in [readme.nodejs.md](./readme.nodejs.md)
 ## TypeScript
 
 See configuration in [readme.typescript.md](./readme.typescript.md)
+
+## Java
+
+See configuration in [readme.java.md](./readme.java.md)