Add comment about not changing strings/enums that are stored persistent

android_app/app/src/main/java/com/health/openscale/core/bodymetric/EstimatedFatMetric.java

@@ -19,6 +19,7 @@ import com.health.openscale.core.datatypes.ScaleMeasurement;
 import com.health.openscale.core.datatypes.ScaleUser;
 
 public abstract class EstimatedFatMetric {
+    // Don't change enum names, they are stored persistent in preferences
     public enum FORMULA { BF_DEURENBERG, BF_DEURENBERG_II, BF_EDDY, BF_GALLAGHER, BF_GALLAGHER_ASIAN }
 
     public static EstimatedFatMetric getEstimatedMetric(FORMULA metric) {

android_app/app/src/main/java/com/health/openscale/core/bodymetric/EstimatedWaterMetric.java

@@ -19,6 +19,7 @@ import com.health.openscale.core.datatypes.ScaleMeasurement;
 import com.health.openscale.core.datatypes.ScaleUser;
 
 public abstract class EstimatedWaterMetric {
+    // Don't change enum names, they are stored persistent in preferences
     public enum FORMULA { TBW_BEHNKE, TBW_DELWAIDECRENIER, TBW_HUMEWEYERS, TBW_LEESONGKIM }
 
     public static EstimatedWaterMetric getEstimatedMetric(FORMULA metric) {

android_app/app/src/main/java/com/health/openscale/gui/views/BMIMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class BMIMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "bmi";
 
     public BMIMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/BMRMeasurementView.java

@@ -27,6 +27,7 @@ import com.health.openscale.core.evaluation.EvaluationSheet;
 import java.util.Locale;
 
 public class BMRMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "bmr";
 
     public BMRMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/BoneMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class BoneMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "bone";
 
     public BoneMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/CommentMeasurementView.java

@@ -26,6 +26,7 @@ import com.health.openscale.R;
 import com.health.openscale.core.datatypes.ScaleMeasurement;
 
 public class CommentMeasurementView extends MeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "comment";
 
     private String comment;

android_app/app/src/main/java/com/health/openscale/gui/views/DateMeasurementView.java

@@ -29,6 +29,7 @@ import java.util.Calendar;
 import java.util.Date;
 
 public class DateMeasurementView extends MeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "date";
 
     private static final DateFormat dateFormat = DateFormat.getDateInstance();

android_app/app/src/main/java/com/health/openscale/gui/views/FatMeasurementView.java

@@ -27,6 +27,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class FatMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "fat";
 
     public FatMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/HipMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class HipMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "hip";
 
     public HipMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/MuscleMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class MuscleMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "muscle";
 
     public MuscleMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/TimeMeasurementView.java

@@ -29,6 +29,7 @@ import java.util.Calendar;
 import java.util.Date;
 
 public class TimeMeasurementView extends MeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "time";
 
     private final DateFormat timeFormat;

android_app/app/src/main/java/com/health/openscale/gui/views/WHRMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class WHRMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "whr";
 
     public WHRMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/WHtRMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class WHtRMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "whtr";
 
     public WHtRMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/WaistMeasurementView.java

@@ -25,6 +25,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class WaistMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "waist";
 
     public WaistMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/WaterMeasurementView.java

@@ -27,6 +27,7 @@ import com.health.openscale.core.evaluation.EvaluationResult;
 import com.health.openscale.core.evaluation.EvaluationSheet;
 
 public class WaterMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "water";
 
     public WaterMeasurementView(Context context) {

android_app/app/src/main/java/com/health/openscale/gui/views/WeightMeasurementView.java

@@ -26,6 +26,7 @@ import com.health.openscale.core.evaluation.EvaluationSheet;
 import com.health.openscale.core.utils.Converters;
 
 public class WeightMeasurementView extends FloatMeasurementView {
+    // Don't change key value, it may be stored persistent in preferences
     public static final String KEY = "weight";
 
     public WeightMeasurementView(Context context) {