provide help for encapsulation error

Author: hauner

openapi-processor-core/src/main/kotlin/io/openapiprocessor/core/writer/java/FormattingException.kt

@@ -5,12 +5,4 @@
 
 package io.openapiprocessor.core.writer.java
 
-class FormattingException(
-    private val source: String,
-    cause: Throwable
-): java.lang.RuntimeException(cause) {
-
-    override val message: String
-        get() = "failed to format the generated source: \n>>\n$source\n<<"
-
-}
+class FormattingException(override val message: String, cause: Throwable): java.lang.RuntimeException(cause)

openapi-processor-core/src/main/kotlin/io/openapiprocessor/core/writer/java/GoogleFormatter.kt

@@ -9,8 +9,10 @@ import com.google.googlejavaformat.java.Formatter
 import com.google.googlejavaformat.java.JavaFormatterOptions
 import io.openapiprocessor.core.writer.SourceFormatter
 
-class GoogleFormatter: SourceFormatter {
-    private lateinit var formatter: Formatter
+private const val addExportsLink: String = "https://openapiprocessor.io/oap/home/jdk.html"
+
+open class GoogleFormatter: SourceFormatter {
+    protected lateinit var formatter: Formatter
 
     init {
         initFormatter()
@@ -19,8 +21,13 @@ class GoogleFormatter: SourceFormatter {
     override fun format(raw: String): String {
         try {
             return correctLineFeed(formatter.formatSource(raw))
+
+        } catch (e: IllegalAccessError) {
+            // since java 16 the jdk.compiler module does not export com.sun.tools.javac.parser
+            throw FormattingException("looks like you may need $addExportsLink to make formatting work.", e)
+
         } catch (e: Exception) {
-            throw FormattingException(raw, e)
+            throw FormattingException("failed to format the generated source: \n>>\n$raw\n<<", e)
         }
     }
 

openapi-processor-core/src/test/kotlin/io/openapiprocessor/core/writer/java/GoogleFormatterSpec.kt

@@ -5,8 +5,12 @@
 
 package io.openapiprocessor.core.writer.java
 
+import com.google.googlejavaformat.java.Formatter
+import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.core.spec.style.StringSpec
 import io.kotest.matchers.shouldBe
+import io.mockk.every
+import io.mockk.mockk
 
 class GoogleFormatterSpec : StringSpec({
 
@@ -19,4 +23,19 @@ class GoogleFormatterSpec : StringSpec({
             |
         """.trimMargin()
     }
+
+    "formatter catches IllegalAccessError and re-throws with link to add-export note" {
+        val f: Formatter = mockk<Formatter>()
+        every { f.formatSource(any()) } throws IllegalAccessError("fake illegal access error")
+
+        val formatter = object: GoogleFormatter() {
+            init {
+                formatter = f
+            }
+        }
+
+        shouldThrow<FormattingException> {
+            formatter.format("....")
+        }
+    }
 })