@NotNull String firstPropertyIfNested(@NotNull String propertyName) {
    """
	Returns the first property from the given property name only if the given property name belongs to a nested
	property. For example, given the nested property "address.street.name", this method will return "address". This
	method returns the given property name unchanged if it does not belong to a nested property.
	
	@param propertyName the given property name.
	@return the first property from the given property name, if the property name belongs to a nested property;
	otherwise, it will return the given property name unchanged.
	@throws NullPointerException if given property name is {@code null}.
    """
    if (!isNestedProperty(propertyName)) {
      return propertyName;
    }
    return checkNotNull(propertyName.substring(0, propertyName.indexOf(SEPARATOR)));
  }
@NotNull String firstPropertyIfNested(@NotNull String propertyName) {
    if (!isNestedProperty(propertyName)) {
      return propertyName;
    }
    return checkNotNull(propertyName.substring(0, propertyName.indexOf(SEPARATOR)));
  }
@ NotNull String firstPropertyIfNested ( @ NotNull String propertyName ) { if ( ! isNestedProperty ( propertyName ) ) { return propertyName ; } return checkNotNull ( propertyName . substring ( 0 , propertyName . indexOf ( SEPARATOR ) ) ) ; }
Returns the first property from the given property name only if the given property name belongs to a nested
property. For example, given the nested property "address.street.name", this method will return "address". This
method returns the given property name unchanged if it does not belong to a nested property.

@param propertyName the given property name.
@return the first property from the given property name, if the property name belongs to a nested property;
otherwise, it will return the given property name unchanged.
@throws NullPointerException if given property name is {@code null}.
Returns the first property from the given property name only if the given property name belongs to a nested property . For example given the nested property address . street . name this method will return address . This method returns the given property name unchanged if it does not belong to a nested property .