[FIR] Make diagnostics collectors returns List instead of Iterable

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/AbstractDiagnosticCollector.kt

@@ -33,7 +33,7 @@ abstract class AbstractDiagnosticCollector(
     override val scopeSession: ScopeSession = ScopeSession(),
     returnTypeCalculator: ReturnTypeCalculator = ReturnTypeCalculatorForFullBodyResolve()
 ) : SessionHolder {
-    fun collectDiagnostics(firFile: FirFile): Iterable<FirDiagnostic<*>> {
+    fun collectDiagnostics(firFile: FirFile): List<FirDiagnostic<*>> {
         if (!componentsInitialized) {
             throw IllegalStateException("Components are not initialized")
         }
@@ -43,7 +43,7 @@ abstract class AbstractDiagnosticCollector(
     }
 
     protected abstract fun initializeCollector()
-    protected abstract fun getCollectedDiagnostics(): Iterable<FirDiagnostic<*>>
+    protected abstract fun getCollectedDiagnostics(): List<FirDiagnostic<*>>
     abstract val reporter: DiagnosticReporter
 
     private val components: MutableList<AbstractDiagnosticCollectorComponent> = mutableListOf()

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/FirDiagnosticsCollector.kt

@@ -8,7 +8,7 @@ package org.jetbrains.kotlin.fir.analysis.collectors
 import org.jetbrains.kotlin.fir.FirSession
 
 object FirDiagnosticsCollector {
-    fun create(session: FirSession): AbstractDiagnosticCollector {
+    fun create(session: FirSession): SimpleDiagnosticsCollector {
         val collector = SimpleDiagnosticsCollector(session)
         collector.registerAllComponents()
         return collector

compiler/fir/checkers/src/org/jetbrains/kotlin/fir/analysis/collectors/SimpleDiagnosticsCollector.kt

@@ -17,7 +17,7 @@ class SimpleDiagnosticsCollector(session: FirSession) : AbstractDiagnosticCollec
         reporter = SimpleDiagnosticReporter()
     }
 
-    override fun getCollectedDiagnostics(): Iterable<FirDiagnostic<*>> {
+    override fun getCollectedDiagnostics(): List<FirDiagnostic<*>> {
         return reporter.diagnostics
     }
 }

idea/idea-frontend-fir/idea-fir-low-level-api/src/org/jetbrains/kotlin/idea/fir/low/level/api/diagnostics/AbstractFirIdeDiagnosticsCollector.kt

@@ -56,7 +56,7 @@ internal abstract class AbstractFirIdeDiagnosticsCollector(
         checkCanceled()
     }
 
-    override fun getCollectedDiagnostics(): Iterable<FirDiagnostic<*>> {
+    override fun getCollectedDiagnostics(): List<FirDiagnostic<*>> {
         // Not necessary in IDE
         return emptyList()
     }