Removed code duplication for getting annotation argument

compiler/frontend/src/org/jetbrains/kotlin/resolve/AnnotationUtil.kt

@@ -19,7 +19,9 @@ package org.jetbrains.kotlin.resolve.annotations
 import org.jetbrains.kotlin.descriptors.CallableDescriptor
 import org.jetbrains.kotlin.descriptors.DeclarationDescriptor
 import org.jetbrains.kotlin.descriptors.PropertyAccessorDescriptor
+import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
 import org.jetbrains.kotlin.name.FqName
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 
 public fun DeclarationDescriptor.hasInlineAnnotation(): Boolean {
@@ -49,3 +51,12 @@ private fun CallableDescriptor.isPlatformStaticIn(predicate: (DeclarationDescrip
             }
             else -> predicate(getContainingDeclaration()) && hasPlatformStaticAnnotation()
         }
+
+public fun AnnotationDescriptor.argumentValue(parameterName: String): Any? {
+    return getAllValueArguments().entrySet()
+            .singleOrNull { it.key.getName().asString() == parameterName }
+            ?.value?.getValue()
+}
+
+public fun AnnotationDescriptor.deprecatedAnnotationMessage(): String?
+        = argumentValue("value") as? String

compiler/frontend/src/org/jetbrains/kotlin/resolve/validation/DeprecatedSymbolValidator.kt

@@ -30,6 +30,8 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.resolve.BindingTrace
 import org.jetbrains.kotlin.resolve.DescriptorUtils
+import org.jetbrains.kotlin.resolve.annotations.argumentValue
+import org.jetbrains.kotlin.resolve.annotations.deprecatedAnnotationMessage
 
 public class DeprecatedSymbolValidator : SymbolUsageValidator {
     private val JAVA_DEPRECATED = FqName(javaClass<Deprecated>().getName())
@@ -89,28 +91,13 @@ public class DeprecatedSymbolValidator : SymbolUsageValidator {
     }
 
     private fun createDeprecationDiagnostic(element: PsiElement, descriptor: DeclarationDescriptor, deprecated: AnnotationDescriptor): Diagnostic {
-        val message = getMessageFromAnnotationDescriptor(deprecated)
+        val message = deprecated.deprecatedAnnotationMessage()
         return if (message == null)
             Errors.DEPRECATED_SYMBOL.on(element, descriptor)
         else
             Errors.DEPRECATED_SYMBOL_WITH_MESSAGE.on(element, descriptor, message)
     }
 
-    private fun getMessageFromAnnotationDescriptor(descriptor: AnnotationDescriptor): String? {
-        val parameterName = Name.identifier("value")
-        for ((parameterDescriptor, argument) in descriptor.getAllValueArguments()) {
-            if (parameterDescriptor.getName() == parameterName) {
-                val parameterValue = argument.getValue()
-                if (parameterValue is String) {
-                    return parameterValue
-                }
-                else
-                    return null
-            }
-        }
-        return null
-    }
-
     private val PROPERTY_SET_OPERATIONS = TokenSet.create(JetTokens.EQ, JetTokens.PLUSEQ, JetTokens.MINUSEQ, JetTokens.MULTEQ, JetTokens.DIVEQ, JetTokens.PERCEQ, JetTokens.PLUSPLUS, JetTokens.MINUSMINUS)
     fun propertyGetterWorkaround(propertyDescriptor: PropertyDescriptor, trace: BindingTrace, expression: PsiElement) {
         // property getters do not come as callable yet, so we analyse surroundings to check for deprecation annotation on getter