Don't copy parameter annotations when creating a ParameterSpec. (#770)

* Don't copy parameter annotations when creating a ParameterSpec.

This further preserves the behaviour discussed in https://github.com/square/javapoet/issues/482.
Unifying it for both MethodSpec.overriding and ParameterSpec.get.

* Add compilation test for when overriding a method with private annotations.

* Address PR comments:

* Remove unused import
* Rename newly added test

4 files changed, 30 insertions, 20 deletions

diff --git a/src/main/java/com/squareup/javapoet/MethodSpec.java b/src/main/java/com/squareup/javapoet/MethodSpec.java
index 2284ef5..67722c7 100644
--- a/src/main/java/com/squareup/javapoet/MethodSpec.java
+++ b/src/main/java/com/squareup/javapoet/MethodSpec.java
@@ -24,7 +24,6 @@ import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
-import java.util.stream.Collectors;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
@@ -233,16 +232,7 @@ public final class MethodSpec {
     }
 
     methodBuilder.returns(TypeName.get(method.getReturnType()));
-    // Copying parameter annotations from the overridden method can be incorrect so we're
-    // deliberately dropping them. See https://github.com/square/javapoet/issues/482.
-    methodBuilder.addParameters(ParameterSpec.parametersOf(method)
-        .stream()
-        .map(parameterSpec -> {
-          ParameterSpec.Builder builder = parameterSpec.toBuilder();
-          builder.annotations.clear();
-          return builder.build();
-        })
-        .collect(Collectors.toList()));
+    methodBuilder.addParameters(ParameterSpec.parametersOf(method));
     methodBuilder.varargs(method.isVarArgs());
 
     for (TypeMirror thrownType : method.getThrownTypes()) {
diff --git a/src/main/java/com/squareup/javapoet/ParameterSpec.java b/src/main/java/com/squareup/javapoet/ParameterSpec.java
index b8f3129..342e657 100644
--- a/src/main/java/com/squareup/javapoet/ParameterSpec.java
+++ b/src/main/java/com/squareup/javapoet/ParameterSpec.java
@@ -21,7 +21,6 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
-import java.util.stream.Collectors;
 import javax.lang.model.SourceVersion;
 import javax.lang.model.element.ElementKind;
 import javax.lang.model.element.ExecutableElement;
@@ -87,17 +86,12 @@ public final class ParameterSpec {
   public static ParameterSpec get(VariableElement element) {
     checkArgument(element.getKind().equals(ElementKind.PARAMETER), "element is not a parameter");
 
-    // Copy over any annotations from element.
-    List<AnnotationSpec> annotations = element.getAnnotationMirrors()
-        .stream()
-        .map((mirror) -> AnnotationSpec.get(mirror))
-        .collect(Collectors.toList());
-
     TypeName type = TypeName.get(element.asType());
     String name = element.getSimpleName().toString();
+    // Copying parameter annotations can be incorrect so we're deliberately not including them.
+    // See https://github.com/square/javapoet/issues/482.
     return ParameterSpec.builder(type, name)
         .addModifiers(element.getModifiers())
-        .addAnnotations(annotations)
         .build();
   }
 
diff --git a/src/test/java/com/squareup/javapoet/MethodSpecTest.java b/src/test/java/com/squareup/javapoet/MethodSpecTest.java
index b768351..824f476 100644
--- a/src/test/java/com/squareup/javapoet/MethodSpecTest.java
+++ b/src/test/java/com/squareup/javapoet/MethodSpecTest.java
@@ -15,6 +15,7 @@
  */
 package com.squareup.javapoet;
 
+import com.google.testing.compile.Compilation;
 import com.google.testing.compile.CompilationRule;
 import java.io.Closeable;
 import java.io.IOException;
@@ -30,14 +31,19 @@ import javax.lang.model.element.ExecutableElement;
 import javax.lang.model.element.Modifier;
 import javax.lang.model.element.TypeElement;
 import javax.lang.model.type.DeclaredType;
+import javax.lang.model.util.ElementFilter;
 import javax.lang.model.util.Elements;
 import javax.lang.model.util.Types;
+import javax.tools.JavaFileObject;
+
+import com.google.testing.compile.CompilationSubject;
 import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 
 import static com.google.common.collect.Iterables.getOnlyElement;
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.testing.compile.Compiler.javac;
 import static com.squareup.javapoet.MethodSpec.CONSTRUCTOR;
 import static com.squareup.javapoet.TestUtil.findFirst;
 import static javax.lang.model.util.ElementFilter.methodsIn;
@@ -247,6 +253,26 @@ public final class MethodSpecTest {
     }
   }
 
+  abstract static class AbstractClassWithPrivateAnnotation {
+
+    private @interface PrivateAnnotation{ }
+
+    abstract void foo(@PrivateAnnotation final String bar);
+  }
+
+  @Test public void overrideDoesNotCopyParameterAnnotations() {
+    TypeElement abstractTypeElement = getElement(AbstractClassWithPrivateAnnotation.class);
+    ExecutableElement fooElement = ElementFilter.methodsIn(abstractTypeElement.getEnclosedElements()).get(0);
+    ClassName implClassName = ClassName.get("com.squareup.javapoet", "Impl");
+    TypeSpec type = TypeSpec.classBuilder(implClassName)
+            .superclass(abstractTypeElement.asType())
+            .addMethod(MethodSpec.overriding(fooElement).build())
+            .build();
+    JavaFileObject jfo = JavaFile.builder(implClassName.packageName, type).build().toJavaFileObject();
+    Compilation compilation = javac().compile(jfo);
+    CompilationSubject.assertThat(compilation).succeeded();
+  }
+
   @Test public void equalsAndHashCode() {
     MethodSpec a = MethodSpec.constructorBuilder().build();
     MethodSpec b = MethodSpec.constructorBuilder().build();
diff --git a/src/test/java/com/squareup/javapoet/ParameterSpecTest.java b/src/test/java/com/squareup/javapoet/ParameterSpecTest.java
index c3effca..8585986 100644
--- a/src/test/java/com/squareup/javapoet/ParameterSpecTest.java
+++ b/src/test/java/com/squareup/javapoet/ParameterSpecTest.java
@@ -99,7 +99,7 @@ public class ParameterSpecTest {
     VariableElement parameterElement = element.getParameters().get(0);
 
     assertThat(ParameterSpec.get(parameterElement).toString())
-        .isEqualTo("@javax.annotation.Nullable java.lang.String arg0");
+        .isEqualTo("java.lang.String arg0");
   }
 
   @Test public void addNonFinalModifier() {