Primer paso de la investigacion. Se aportan el .apk, las carpetas con el apk extraido y el apk descompilado. El archivo API_DOCUMENTATION.md es un archivo donde se anotaran los descubrimientos del funcionamiento de la API, y los .py son scripts para probar la funcionalidad de la API con los métodos que vayamos encontrando. Finalmente, los archivos .js son scripts de Frida para extraer informacion de la APP durante la ejecucion.

apk_decompiled/sources/kotlin/text/StringsKt__AppendableKt.java

@@ -0,0 +1,80 @@
+package kotlin.text;
+
+import kotlin.ExperimentalStdlibApi;
+import kotlin.Metadata;
+import kotlin.SinceKotlin;
+import kotlin.WasExperimental;
+import kotlin.internal.InlineOnly;
+import kotlin.jvm.functions.Function1;
+import kotlin.jvm.internal.Intrinsics;
+
+/* JADX INFO: Access modifiers changed from: package-private */
+@Metadata(d1 = {"\u0000:\n\u0002\b\u0002\n\u0002\u0018\u0002\n\u0002\u0018\u0002\n\u0000\n\u0002\u0010\u0011\n\u0002\u0010\r\n\u0002\b\u0002\n\u0002\u0010\u0002\n\u0002\b\u0002\n\u0002\u0018\u0002\n\u0002\b\u0002\n\u0002\u0010\f\n\u0002\b\u0002\n\u0002\u0010\b\n\u0002\b\u0003\u001a5\u0010\u0000\u001a\u0002H\u0001\"\f\b\u0000\u0010\u0001*\u00060\u0002j\u0002`\u0003*\u0002H\u00012\u0016\u0010\u0004\u001a\f\u0012\b\b\u0001\u0012\u0004\u0018\u00010\u00060\u0005\"\u0004\u0018\u00010\u0006¢\u0006\u0002\u0010\u0007\u001a9\u0010\b\u001a\u00020\t\"\u0004\b\u0000\u0010\u0001*\u00060\u0002j\u0002`\u00032\u0006\u0010\n\u001a\u0002H\u00012\u0014\u0010\u000b\u001a\u0010\u0012\u0004\u0012\u0002H\u0001\u0012\u0004\u0012\u00020\u0006\u0018\u00010\fH\u0000¢\u0006\u0002\u0010\r\u001a\u0015\u0010\u000e\u001a\u00060\u0002j\u0002`\u0003*\u00060\u0002j\u0002`\u0003H\u0087\b\u001a\u001d\u0010\u000e\u001a\u00060\u0002j\u0002`\u0003*\u00060\u0002j\u0002`\u00032\u0006\u0010\u0004\u001a\u00020\u000fH\u0087\b\u001a\u001f\u0010\u000e\u001a\u00060\u0002j\u0002`\u0003*\u00060\u0002j\u0002`\u00032\b\u0010\u0004\u001a\u0004\u0018\u00010\u0006H\u0087\b\u001a7\u0010\u0010\u001a\u0002H\u0001\"\f\b\u0000\u0010\u0001*\u00060\u0002j\u0002`\u0003*\u0002H\u00012\u0006\u0010\u0004\u001a\u00020\u00062\u0006\u0010\u0011\u001a\u00020\u00122\u0006\u0010\u0013\u001a\u00020\u0012H\u0007¢\u0006\u0002\u0010\u0014¨\u0006\u0015"}, d2 = {"append", "T", "Ljava/lang/Appendable;", "Lkotlin/text/Appendable;", "value", "", "", "(Ljava/lang/Appendable;[Ljava/lang/CharSequence;)Ljava/lang/Appendable;", "appendElement", "", "element", "transform", "Lkotlin/Function1;", "(Ljava/lang/Appendable;Ljava/lang/Object;Lkotlin/jvm/functions/Function1;)V", "appendLine", "", "appendRange", "startIndex", "", "endIndex", "(Ljava/lang/Appendable;Ljava/lang/CharSequence;II)Ljava/lang/Appendable;", "kotlin-stdlib"}, k = 5, mv = {1, 9, 0}, xi = 49, xs = "kotlin/text/StringsKt")
+/* loaded from: classes3.dex */
+public class StringsKt__AppendableKt {
+    public static final <T extends Appendable> T append(T t2, CharSequence... value) {
+        Intrinsics.checkNotNullParameter(t2, "<this>");
+        Intrinsics.checkNotNullParameter(value, "value");
+        for (CharSequence charSequence : value) {
+            t2.append(charSequence);
+        }
+        return t2;
+    }
+
+    /* JADX WARN: Multi-variable type inference failed */
+    public static <T> void appendElement(Appendable appendable, T t2, Function1<? super T, ? extends CharSequence> function1) {
+        Intrinsics.checkNotNullParameter(appendable, "<this>");
+        if (function1 != null) {
+            appendable.append(function1.invoke(t2));
+            return;
+        }
+        if (t2 == 0 ? true : t2 instanceof CharSequence) {
+            appendable.append((CharSequence) t2);
+        } else if (t2 instanceof Character) {
+            appendable.append(((Character) t2).charValue());
+        } else {
+            appendable.append(String.valueOf(t2));
+        }
+    }
+
+    @SinceKotlin(version = "1.4")
+    @InlineOnly
+    private static final Appendable appendLine(Appendable appendable) {
+        Intrinsics.checkNotNullParameter(appendable, "<this>");
+        Appendable append = appendable.append('\n');
+        Intrinsics.checkNotNullExpressionValue(append, "append(...)");
+        return append;
+    }
+
+    @SinceKotlin(version = "1.4")
+    @WasExperimental(markerClass = {ExperimentalStdlibApi.class})
+    public static final <T extends Appendable> T appendRange(T t2, CharSequence value, int i, int i4) {
+        Intrinsics.checkNotNullParameter(t2, "<this>");
+        Intrinsics.checkNotNullParameter(value, "value");
+        T t4 = (T) t2.append(value, i, i4);
+        Intrinsics.checkNotNull(t4, "null cannot be cast to non-null type T of kotlin.text.StringsKt__AppendableKt.appendRange");
+        return t4;
+    }
+
+    @SinceKotlin(version = "1.4")
+    @InlineOnly
+    private static final Appendable appendLine(Appendable appendable, CharSequence charSequence) {
+        Intrinsics.checkNotNullParameter(appendable, "<this>");
+        Appendable append = appendable.append(charSequence);
+        Intrinsics.checkNotNullExpressionValue(append, "append(...)");
+        Appendable append2 = append.append('\n');
+        Intrinsics.checkNotNullExpressionValue(append2, "append(...)");
+        return append2;
+    }
+
+    @SinceKotlin(version = "1.4")
+    @InlineOnly
+    private static final Appendable appendLine(Appendable appendable, char c4) {
+        Intrinsics.checkNotNullParameter(appendable, "<this>");
+        Appendable append = appendable.append(c4);
+        Intrinsics.checkNotNullExpressionValue(append, "append(...)");
+        Appendable append2 = append.append('\n');
+        Intrinsics.checkNotNullExpressionValue(append2, "append(...)");
+        return append2;
+    }
+}