Inspection: convert initialized val to non-null type

^KT-35757 Fixed

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/.inspection

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.inspections.ConvertInitializedValToNonNullTypeInspection

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/assignToMethodCall.kt

@@ -0,0 +1,5 @@
+fun foo() {
+    val s1: String?<caret> = bar()
+}
+
+fun bar(): String = ""

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/assignToMethodCall.kt.after

@@ -0,0 +1,5 @@
+fun foo() {
+    val s1: String = bar()
+}
+
+fun bar(): String = ""

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/assignToVariable.kt

@@ -0,0 +1,4 @@
+fun foo() {
+    val s0: String = ""
+    val s1: String?<caret> = s0
+}

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/assignToVariable.kt.after

@@ -0,0 +1,4 @@
+fun foo() {
+    val s0: String = ""
+    val s1: String = s0
+}

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/basic.kt

@@ -0,0 +1,3 @@
+fun foo() {
+    val s: String?<caret> = "Hello"
+}

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/basic.kt.after

@@ -0,0 +1,3 @@
+fun foo() {
+    val s: String = "Hello"
+}

idea/testData/inspectionsLocal/convertInitializedValToNonNullType/negative.kt

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+// PROBLEM: none
+fun foo() {
+    val s1: String? = bar()
+    val s2: String?<caret> = null
+}
+
+fun bar(): String? = ""