Provide equals/hashCode based on original PSI to avoid potential PCEs

#KT-59445

compiler/resolution.common.jvm/src/org/jetbrains/kotlin/load/java/structure/impl/source/JavaElementPsiSource.kt

@@ -18,6 +18,12 @@ class JavaElementPsiSourceWithFixedPsi<PSI : PsiElement>(
     override val factory: JavaElementSourceFactory
         get() = JavaElementSourceFactory.getInstance(psi.project)
 
+    override fun equals(other: Any?): Boolean {
+        return if (other === this) true else other is JavaElementPsiSourceWithFixedPsi<*> && psi == other.psi
+    }
+
+    override fun hashCode(): Int = psi.hashCode()
+
     override fun toString(): String {
         return psi.toString()
     }