rename getKey to getString

pdb-api/src/main/java/org/lucares/pdb/api/StringCompressor.java

@@ -49,7 +49,7 @@ public class StringCompressor {
 
     public String getString(final int integer) {
 
-        return usip.getKey(integer);
+        return usip.getString(integer);
     }
 
     public int getIfPresent(final String string) {

pdb-api/src/main/java/org/lucares/pdb/api/UniqueStringIntegerPairs.java

@@ -184,7 +184,7 @@ public class UniqueStringIntegerPairs {
         return stringToInt.get(string);
     }
 
-    public String getKey(final int second) {
+    public String getString(final int second) {
         return intToString.get(second);
     }
 

pdb-api/src/test/java/org/lucares/pdb/api/UniqueStringIntegerPairsTest.java

@@ -35,14 +35,14 @@ public class UniqueStringIntegerPairsTest {
 
             usip.putStringAndInteger(first, second);
             Assertions.assertEquals(second, usip.getInt(first));
-            Assertions.assertEquals(first, usip.getKey(second));
+            Assertions.assertEquals(first, usip.getString(second));
         }
 
         {
             final UniqueStringIntegerPairs usip = new UniqueStringIntegerPairs(database);
 
             Assertions.assertEquals(second, usip.getInt(first));
-            Assertions.assertEquals(first, usip.getKey(second));
+            Assertions.assertEquals(first, usip.getString(second));
         }
     }